Theta Smart Contracts | ThetaScan.io

Node:

Token Contract Details

Contract:

0x447839df51476fab87deb1a366cb095777ccabdc

Name:

ThetaWisdom PP - Live Event

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Published Contract:

// SPDX-License-Identifier: MIT

// File: @openzeppelin/contracts/utils/math/Math.sol


// OpenZeppelin Contracts (last updated v4.7.0) (utils/math/Math.sol)

pragma solidity ^0.8.0;

/**
 * @dev Standard math utilities missing in the Solidity language.
 */
library Math {
 enum Rounding {
 Down, // Toward negative infinity
 Up, // Toward infinity
 Zero // Toward zero
 }

 /**
 * @dev Returns the largest of two numbers.
 */
 function max(uint256 a, uint256 b) internal pure returns (uint256) {
 return a >= b ? a : b;
 }

 /**
 * @dev Returns the smallest of two numbers.
 */
 function min(uint256 a, uint256 b) internal pure returns (uint256) {
 return a < b ? a : b;
 }

 /**
 * @dev Returns the average of two numbers. The result is rounded towards
 * zero.
 */
 function average(uint256 a, uint256 b) internal pure returns (uint256) {
 // (a + b) / 2 can overflow.
 return (a & b) + (a ^ b) / 2;
 }

 /**
 * @dev Returns the ceiling of the division of two numbers.
 *
 * This differs from standard division with `/` in that it rounds up instead
 * of rounding down.
 */
 function ceilDiv(uint256 a, uint256 b) internal pure returns (uint256) {
 // (a + b - 1) / b can overflow on addition, so we distribute.
 return a == 0 ? 0 : (a - 1) / b + 1;
 }

 /**
 * @notice Calculates floor(x * y / denominator) with full precision. Throws if result overflows a uint256 or denominator == 0
 * @dev Original credit to Remco Bloemen under MIT license (https://xn--2-umb.com/21/muldiv)
 * with further edits by Uniswap Labs also under MIT license.
 */
 function mulDiv(
 uint256 x,
 uint256 y,
 uint256 denominator
 ) internal pure returns (uint256 result) {
 unchecked {
 // 512-bit multiply [prod1 prod0] = x * y. Compute the product mod 2^256 and mod 2^256 - 1, then use
 // use the Chinese Remainder Theorem to reconstruct the 512 bit result. The result is stored in two 256
 // variables such that product = prod1 * 2^256 + prod0.
 uint256 prod0; // Least significant 256 bits of the product
 uint256 prod1; // Most significant 256 bits of the product
 assembly {
 let mm := mulmod(x, y, not(0))
 prod0 := mul(x, y)
 prod1 := sub(sub(mm, prod0), lt(mm, prod0))
 }

 // Handle non-overflow cases, 256 by 256 division.
 if (prod1 == 0) {
 return prod0 / denominator;
 }

 // Make sure the result is less than 2^256. Also prevents denominator == 0.
 require(denominator > prod1);

 ///////////////////////////////////////////////
 // 512 by 256 division.
 ///////////////////////////////////////////////

 // Make division exact by subtracting the remainder from [prod1 prod0].
 uint256 remainder;
 assembly {
 // Compute remainder using mulmod.
 remainder := mulmod(x, y, denominator)

 // Subtract 256 bit number from 512 bit number.
 prod1 := sub(prod1, gt(remainder, prod0))
 prod0 := sub(prod0, remainder)
 }

 // Factor powers of two out of denominator and compute largest power of two divisor of denominator. Always >= 1.
 // See https://cs.stackexchange.com/q/138556/92363.

 // Does not overflow because the denominator cannot be zero at this stage in the function.
 uint256 twos = denominator & (~denominator + 1);
 assembly {
 // Divide denominator by twos.
 denominator := div(denominator, twos)

 // Divide [prod1 prod0] by twos.
 prod0 := div(prod0, twos)

 // Flip twos such that it is 2^256 / twos. If twos is zero, then it becomes one.
 twos := add(div(sub(0, twos), twos), 1)
 }

 // Shift in bits from prod1 into prod0.
 prod0 |= prod1 * twos;

 // Invert denominator mod 2^256. Now that denominator is an odd number, it has an inverse modulo 2^256 such
 // that denominator * inv = 1 mod 2^256. Compute the inverse by starting with a seed that is correct for
 // four bits. That is, denominator * inv = 1 mod 2^4.
 uint256 inverse = (3 * denominator) ^ 2;

 // Use the Newton-Raphson iteration to improve the precision. Thanks to Hensel9s lifting lemma, this also works
 // in modular arithmetic, doubling the correct bits in each step.
 inverse *= 2 - denominator * inverse; // inverse mod 2^8
 inverse *= 2 - denominator * inverse; // inverse mod 2^16
 inverse *= 2 - denominator * inverse; // inverse mod 2^32
 inverse *= 2 - denominator * inverse; // inverse mod 2^64
 inverse *= 2 - denominator * inverse; // inverse mod 2^128
 inverse *= 2 - denominator * inverse; // inverse mod 2^256

 // Because the division is now exact we can divide by multiplying with the modular inverse of denominator.
 // This will give us the correct result modulo 2^256. Since the preconditions guarantee that the outcome is
 // less than 2^256, this is the final result. We don9t need to compute the high bits of the result and prod1
 // is no longer required.
 result = prod0 * inverse;
 return result;
 }
 }

 /**
 * @notice Calculates x * y / denominator with full precision, following the selected rounding direction.
 */
 function mulDiv(
 uint256 x,
 uint256 y,
 uint256 denominator,
 Rounding rounding
 ) internal pure returns (uint256) {
 uint256 result = mulDiv(x, y, denominator);
 if (rounding == Rounding.Up && mulmod(x, y, denominator) > 0) {
 result += 1;
 }
 return result;
 }

 /**
 * @dev Returns the square root of a number. It the number is not a perfect square, the value is rounded down.
 *
 * Inspired by Henry S. Warren, Jr.9s "Hacker9s Delight" (Chapter 11).
 */
 function sqrt(uint256 a) internal pure returns (uint256) {
 if (a == 0) {
 return 0;
 }

 // For our first guess, we get the biggest power of 2 which is smaller than the square root of the target.
 // We know that the "msb" (most significant bit) of our target number `a` is a power of 2 such that we have
 // `msb(a) <= a < 2*msb(a)`.
 // We also know that `k`, the position of the most significant bit, is such that `msb(a) = 2**k`.
 // This gives `2**k < a <= 2**(k+1)` → `2**(k/2) <= sqrt(a) < 2 ** (k/2+1)`.
 // Using an algorithm similar to the msb conmputation, we are able to compute `result = 2**(k/2)` which is a
 // good first aproximation of `sqrt(a)` with at least 1 correct bit.
 uint256 result = 1;
 uint256 x = a;
 if (x >> 128 > 0) {
 x >>= 128;
 result <<= 64;
 }
 if (x >> 64 > 0) {
 x >>= 64;
 result <<= 32;
 }
 if (x >> 32 > 0) {
 x >>= 32;
 result <<= 16;
 }
 if (x >> 16 > 0) {
 x >>= 16;
 result <<= 8;
 }
 if (x >> 8 > 0) {
 x >>= 8;
 result <<= 4;
 }
 if (x >> 4 > 0) {
 x >>= 4;
 result <<= 2;
 }
 if (x >> 2 > 0) {
 result <<= 1;
 }

 // At this point `result` is an estimation with one bit of precision. We know the true value is a uint128,
 // since it is the square root of a uint256. Newton9s method converges quadratically (precision doubles at
 // every iteration). We thus need at most 7 iteration to turn our partial result with one bit of precision
 // into the expected uint128 result.
 unchecked {
 result = (result + a / result) >> 1;
 result = (result + a / result) >> 1;
 result = (result + a / result) >> 1;
 result = (result + a / result) >> 1;
 result = (result + a / result) >> 1;
 result = (result + a / result) >> 1;
 result = (result + a / result) >> 1;
 return min(result, a / result);
 }
 }

 /**
 * @notice Calculates sqrt(a), following the selected rounding direction.
 */
 function sqrt(uint256 a, Rounding rounding) internal pure returns (uint256) {
 uint256 result = sqrt(a);
 if (rounding == Rounding.Up && result * result < a) {
 result += 1;
 }
 return result;
 }
}

// File: @openzeppelin/contracts/utils/structs/EnumerableSet.sol


// OpenZeppelin Contracts (last updated v4.7.0) (utils/structs/EnumerableSet.sol)

pragma solidity ^0.8.0;

/**
 * @dev Library for managing
 * https://en.wikipedia.org/wiki/Set_(abstract_data_type)[sets] of primitive
 * types.
 *
 * Sets have the following properties:
 *
 * - Elements are added, removed, and checked for existence in constant time
 * (O(1)).
 * - Elements are enumerated in O(n). No guarantees are made on the ordering.
 *
 * ```
 * contract Example {
 * // Add the library methods
 * using EnumerableSet for EnumerableSet.AddressSet;
 *
 * // Declare a set state variable
 * EnumerableSet.AddressSet private mySet;
 * }
 * ```
 *
 * As of v3.3.0, sets of type `bytes32` (`Bytes32Set`), `address` (`AddressSet`)
 * and `uint256` (`UintSet`) are supported.
 *
 * [WARNING]
 * ====
 * Trying to delete such a structure from storage will likely result in data corruption, rendering the structure unusable.
 * See https://github.com/ethereum/solidity/pull/11843[ethereum/solidity#11843] for more info.
 *
 * In order to clean an EnumerableSet, you can either remove all elements one by one or create a fresh instance using an array of EnumerableSet.
 * ====
 */
library EnumerableSet {
 // To implement this library for multiple types with as little code
 // repetition as possible, we write it in terms of a generic Set type with
 // bytes32 values.
 // The Set implementation uses private functions, and user-facing
 // implementations (such as AddressSet) are just wrappers around the
 // underlying Set.
 // This means that we can only create new EnumerableSets for types that fit
 // in bytes32.

 struct Set {
 // Storage of set values
 bytes32[] _values;
 // Position of the value in the `values` array, plus 1 because index 0
 // means a value is not in the set.
 mapping(bytes32 => uint256) _indexes;
 }

 /**
 * @dev Add a value to a set. O(1).
 *
 * Returns true if the value was added to the set, that is if it was not
 * already present.
 */
 function _add(Set storage set, bytes32 value) private returns (bool) {
 if (!_contains(set, value)) {
 set._values.push(value);
 // The value is stored at length-1, but we add 1 to all indexes
 // and use 0 as a sentinel value
 set._indexes[value] = set._values.length;
 return true;
 } else {
 return false;
 }
 }

 /**
 * @dev Removes a value from a set. O(1).
 *
 * Returns true if the value was removed from the set, that is if it was
 * present.
 */
 function _remove(Set storage set, bytes32 value) private returns (bool) {
 // We read and store the value9s index to prevent multiple reads from the same storage slot
 uint256 valueIndex = set._indexes[value];

 if (valueIndex != 0) {
 // Equivalent to contains(set, value)
 // To delete an element from the _values array in O(1), we swap the element to delete with the last one in
 // the array, and then remove the last element (sometimes called as 9swap and pop9).
 // This modifies the order of the array, as noted in {at}.

 uint256 toDeleteIndex = valueIndex - 1;
 uint256 lastIndex = set._values.length - 1;

 if (lastIndex != toDeleteIndex) {
 bytes32 lastValue = set._values[lastIndex];

 // Move the last value to the index where the value to delete is
 set._values[toDeleteIndex] = lastValue;
 // Update the index for the moved value
 set._indexes[lastValue] = valueIndex; // Replace lastValue9s index to valueIndex
 }

 // Delete the slot where the moved value was stored
 set._values.pop();

 // Delete the index for the deleted slot
 delete set._indexes[value];

 return true;
 } else {
 return false;
 }
 }

 /**
 * @dev Returns true if the value is in the set. O(1).
 */
 function _contains(Set storage set, bytes32 value) private view returns (bool) {
 return set._indexes[value] != 0;
 }

 /**
 * @dev Returns the number of values on the set. O(1).
 */
 function _length(Set storage set) private view returns (uint256) {
 return set._values.length;
 }

 /**
 * @dev Returns the value stored at position `index` in the set. O(1).
 *
 * Note that there are no guarantees on the ordering of values inside the
 * array, and it may change when more values are added or removed.
 *
 * Requirements:
 *
 * - `index` must be strictly less than {length}.
 */
 function _at(Set storage set, uint256 index) private view returns (bytes32) {
 return set._values[index];
 }

 /**
 * @dev Return the entire set in an array
 *
 * WARNING: This operation will copy the entire storage to memory, which can be quite expensive. This is designed
 * to mostly be used by view accessors that are queried without any gas fees. Developers should keep in mind that
 * this function has an unbounded cost, and using it as part of a state-changing function may render the function
 * uncallable if the set grows to a point where copying to memory consumes too much gas to fit in a block.
 */
 function _values(Set storage set) private view returns (bytes32[] memory) {
 return set._values;
 }

 // Bytes32Set

 struct Bytes32Set {
 Set _inner;
 }

 /**
 * @dev Add a value to a set. O(1).
 *
 * Returns true if the value was added to the set, that is if it was not
 * already present.
 */
 function add(Bytes32Set storage set, bytes32 value) internal returns (bool) {
 return _add(set._inner, value);
 }

 /**
 * @dev Removes a value from a set. O(1).
 *
 * Returns true if the value was removed from the set, that is if it was
 * present.
 */
 function remove(Bytes32Set storage set, bytes32 value) internal returns (bool) {
 return _remove(set._inner, value);
 }

 /**
 * @dev Returns true if the value is in the set. O(1).
 */
 function contains(Bytes32Set storage set, bytes32 value) internal view returns (bool) {
 return _contains(set._inner, value);
 }

 /**
 * @dev Returns the number of values in the set. O(1).
 */
 function length(Bytes32Set storage set) internal view returns (uint256) {
 return _length(set._inner);
 }

 /**
 * @dev Returns the value stored at position `index` in the set. O(1).
 *
 * Note that there are no guarantees on the ordering of values inside the
 * array, and it may change when more values are added or removed.
 *
 * Requirements:
 *
 * - `index` must be strictly less than {length}.
 */
 function at(Bytes32Set storage set, uint256 index) internal view returns (bytes32) {
 return _at(set._inner, index);
 }

 /**
 * @dev Return the entire set in an array
 *
 * WARNING: This operation will copy the entire storage to memory, which can be quite expensive. This is designed
 * to mostly be used by view accessors that are queried without any gas fees. Developers should keep in mind that
 * this function has an unbounded cost, and using it as part of a state-changing function may render the function
 * uncallable if the set grows to a point where copying to memory consumes too much gas to fit in a block.
 */
 function values(Bytes32Set storage set) internal view returns (bytes32[] memory) {
 return _values(set._inner);
 }

 // AddressSet

 struct AddressSet {
 Set _inner;
 }

 /**
 * @dev Add a value to a set. O(1).
 *
 * Returns true if the value was added to the set, that is if it was not
 * already present.
 */
 function add(AddressSet storage set, address value) internal returns (bool) {
 return _add(set._inner, bytes32(uint256(uint160(value))));
 }

 /**
 * @dev Removes a value from a set. O(1).
 *
 * Returns true if the value was removed from the set, that is if it was
 * present.
 */
 function remove(AddressSet storage set, address value) internal returns (bool) {
 return _remove(set._inner, bytes32(uint256(uint160(value))));
 }

 /**
 * @dev Returns true if the value is in the set. O(1).
 */
 function contains(AddressSet storage set, address value) internal view returns (bool) {
 return _contains(set._inner, bytes32(uint256(uint160(value))));
 }

 /**
 * @dev Returns the number of values in the set. O(1).
 */
 function length(AddressSet storage set) internal view returns (uint256) {
 return _length(set._inner);
 }

 /**
 * @dev Returns the value stored at position `index` in the set. O(1).
 *
 * Note that there are no guarantees on the ordering of values inside the
 * array, and it may change when more values are added or removed.
 *
 * Requirements:
 *
 * - `index` must be strictly less than {length}.
 */
 function at(AddressSet storage set, uint256 index) internal view returns (address) {
 return address(uint160(uint256(_at(set._inner, index))));
 }

 /**
 * @dev Return the entire set in an array
 *
 * WARNING: This operation will copy the entire storage to memory, which can be quite expensive. This is designed
 * to mostly be used by view accessors that are queried without any gas fees. Developers should keep in mind that
 * this function has an unbounded cost, and using it as part of a state-changing function may render the function
 * uncallable if the set grows to a point where copying to memory consumes too much gas to fit in a block.
 */
 function values(AddressSet storage set) internal view returns (address[] memory) {
 bytes32[] memory store = _values(set._inner);
 address[] memory result;

 /// @solidity memory-safe-assembly
 assembly {
 result := store
 }

 return result;
 }

 // UintSet

 struct UintSet {
 Set _inner;
 }

 /**
 * @dev Add a value to a set. O(1).
 *
 * Returns true if the value was added to the set, that is if it was not
 * already present.
 */
 function add(UintSet storage set, uint256 value) internal returns (bool) {
 return _add(set._inner, bytes32(value));
 }

 /**
 * @dev Removes a value from a set. O(1).
 *
 * Returns true if the value was removed from the set, that is if it was
 * present.
 */
 function remove(UintSet storage set, uint256 value) internal returns (bool) {
 return _remove(set._inner, bytes32(value));
 }

 /**
 * @dev Returns true if the value is in the set. O(1).
 */
 function contains(UintSet storage set, uint256 value) internal view returns (bool) {
 return _contains(set._inner, bytes32(value));
 }

 /**
 * @dev Returns the number of values on the set. O(1).
 */
 function length(UintSet storage set) internal view returns (uint256) {
 return _length(set._inner);
 }

 /**
 * @dev Returns the value stored at position `index` in the set. O(1).
 *
 * Note that there are no guarantees on the ordering of values inside the
 * array, and it may change when more values are added or removed.
 *
 * Requirements:
 *
 * - `index` must be strictly less than {length}.
 */
 function at(UintSet storage set, uint256 index) internal view returns (uint256) {
 return uint256(_at(set._inner, index));
 }

 /**
 * @dev Return the entire set in an array
 *
 * WARNING: This operation will copy the entire storage to memory, which can be quite expensive. This is designed
 * to mostly be used by view accessors that are queried without any gas fees. Developers should keep in mind that
 * this function has an unbounded cost, and using it as part of a state-changing function may render the function
 * uncallable if the set grows to a point where copying to memory consumes too much gas to fit in a block.
 */
 function values(UintSet storage set) internal view returns (uint256[] memory) {
 bytes32[] memory store = _values(set._inner);
 uint256[] memory result;

 /// @solidity memory-safe-assembly
 assembly {
 result := store
 }

 return result;
 }
}

// File: @openzeppelin/contracts/utils/structs/EnumerableMap.sol


// OpenZeppelin Contracts (last updated v4.7.0) (utils/structs/EnumerableMap.sol)

pragma solidity ^0.8.0;


/**
 * @dev Library for managing an enumerable variant of Solidity9s
 * https://solidity.readthedocs.io/en/latest/types.html#mapping-types[`mapping`]
 * type.
 *
 * Maps have the following properties:
 *
 * - Entries are added, removed, and checked for existence in constant time
 * (O(1)).
 * - Entries are enumerated in O(n). No guarantees are made on the ordering.
 *
 * ```
 * contract Example {
 * // Add the library methods
 * using EnumerableMap for EnumerableMap.UintToAddressMap;
 *
 * // Declare a set state variable
 * EnumerableMap.UintToAddressMap private myMap;
 * }
 * ```
 *
 * The following map types are supported:
 *
 * - `uint256 -> address` (`UintToAddressMap`) since v3.0.0
 * - `address -> uint256` (`AddressToUintMap`) since v4.6.0
 * - `bytes32 -> bytes32` (`Bytes32ToBytes32`) since v4.6.0
 * - `uint256 -> uint256` (`UintToUintMap`) since v4.7.0
 * - `bytes32 -> uint256` (`Bytes32ToUintMap`) since v4.7.0
 *
 * [WARNING]
 * ====
 * Trying to delete such a structure from storage will likely result in data corruption, rendering the structure unusable.
 * See https://github.com/ethereum/solidity/pull/11843[ethereum/solidity#11843] for more info.
 *
 * In order to clean an EnumerableMap, you can either remove all elements one by one or create a fresh instance using an array of EnumerableMap.
 * ====
 */
library EnumerableMap {
 using EnumerableSet for EnumerableSet.Bytes32Set;

 // To implement this library for multiple types with as little code
 // repetition as possible, we write it in terms of a generic Map type with
 // bytes32 keys and values.
 // The Map implementation uses private functions, and user-facing
 // implementations (such as Uint256ToAddressMap) are just wrappers around
 // the underlying Map.
 // This means that we can only create new EnumerableMaps for types that fit
 // in bytes32.

 struct Bytes32ToBytes32Map {
 // Storage of keys
 EnumerableSet.Bytes32Set _keys;
 mapping(bytes32 => bytes32) _values;
 }

 /**
 * @dev Adds a key-value pair to a map, or updates the value for an existing
 * key. O(1).
 *
 * Returns true if the key was added to the map, that is if it was not
 * already present.
 */
 function set(
 Bytes32ToBytes32Map storage map,
 bytes32 key,
 bytes32 value
 ) internal returns (bool) {
 map._values[key] = value;
 return map._keys.add(key);
 }

 /**
 * @dev Removes a key-value pair from a map. O(1).
 *
 * Returns true if the key was removed from the map, that is if it was present.
 */
 function remove(Bytes32ToBytes32Map storage map, bytes32 key) internal returns (bool) {
 delete map._values[key];
 return map._keys.remove(key);
 }

 /**
 * @dev Returns true if the key is in the map. O(1).
 */
 function contains(Bytes32ToBytes32Map storage map, bytes32 key) internal view returns (bool) {
 return map._keys.contains(key);
 }

 /**
 * @dev Returns the number of key-value pairs in the map. O(1).
 */
 function length(Bytes32ToBytes32Map storage map) internal view returns (uint256) {
 return map._keys.length();
 }

 /**
 * @dev Returns the key-value pair stored at position `index` in the map. O(1).
 *
 * Note that there are no guarantees on the ordering of entries inside the
 * array, and it may change when more entries are added or removed.
 *
 * Requirements:
 *
 * - `index` must be strictly less than {length}.
 */
 function at(Bytes32ToBytes32Map storage map, uint256 index) internal view returns (bytes32, bytes32) {
 bytes32 key = map._keys.at(index);
 return (key, map._values[key]);
 }

 /**
 * @dev Tries to returns the value associated with `key`. O(1).
 * Does not revert if `key` is not in the map.
 */
 function tryGet(Bytes32ToBytes32Map storage map, bytes32 key) internal view returns (bool, bytes32) {
 bytes32 value = map._values[key];
 if (value == bytes32(0)) {
 return (contains(map, key), bytes32(0));
 } else {
 return (true, value);
 }
 }

 /**
 * @dev Returns the value associated with `key`. O(1).
 *
 * Requirements:
 *
 * - `key` must be in the map.
 */
 function get(Bytes32ToBytes32Map storage map, bytes32 key) internal view returns (bytes32) {
 bytes32 value = map._values[key];
 require(value != 0 || contains(map, key), "EnumerableMap: nonexistent key");
 return value;
 }

 /**
 * @dev Same as {_get}, with a custom error message when `key` is not in the map.
 *
 * CAUTION: This function is deprecated because it requires allocating memory for the error
 * message unnecessarily. For custom revert reasons use {_tryGet}.
 */
 function get(
 Bytes32ToBytes32Map storage map,
 bytes32 key,
 string memory errorMessage
 ) internal view returns (bytes32) {
 bytes32 value = map._values[key];
 require(value != 0 || contains(map, key), errorMessage);
 return value;
 }

 // UintToUintMap

 struct UintToUintMap {
 Bytes32ToBytes32Map _inner;
 }

 /**
 * @dev Adds a key-value pair to a map, or updates the value for an existing
 * key. O(1).
 *
 * Returns true if the key was added to the map, that is if it was not
 * already present.
 */
 function set(
 UintToUintMap storage map,
 uint256 key,
 uint256 value
 ) internal returns (bool) {
 return set(map._inner, bytes32(key), bytes32(value));
 }

 /**
 * @dev Removes a value from a set. O(1).
 *
 * Returns true if the key was removed from the map, that is if it was present.
 */
 function remove(UintToUintMap storage map, uint256 key) internal returns (bool) {
 return remove(map._inner, bytes32(key));
 }

 /**
 * @dev Returns true if the key is in the map. O(1).
 */
 function contains(UintToUintMap storage map, uint256 key) internal view returns (bool) {
 return contains(map._inner, bytes32(key));
 }

 /**
 * @dev Returns the number of elements in the map. O(1).
 */
 function length(UintToUintMap storage map) internal view returns (uint256) {
 return length(map._inner);
 }

 /**
 * @dev Returns the element stored at position `index` in the set. O(1).
 * Note that there are no guarantees on the ordering of values inside the
 * array, and it may change when more values are added or removed.
 *
 * Requirements:
 *
 * - `index` must be strictly less than {length}.
 */
 function at(UintToUintMap storage map, uint256 index) internal view returns (uint256, uint256) {
 (bytes32 key, bytes32 value) = at(map._inner, index);
 return (uint256(key), uint256(value));
 }

 /**
 * @dev Tries to returns the value associated with `key`. O(1).
 * Does not revert if `key` is not in the map.
 */
 function tryGet(UintToUintMap storage map, uint256 key) internal view returns (bool, uint256) {
 (bool success, bytes32 value) = tryGet(map._inner, bytes32(key));
 return (success, uint256(value));
 }

 /**
 * @dev Returns the value associated with `key`. O(1).
 *
 * Requirements:
 *
 * - `key` must be in the map.
 */
 function get(UintToUintMap storage map, uint256 key) internal view returns (uint256) {
 return uint256(get(map._inner, bytes32(key)));
 }

 /**
 * @dev Same as {get}, with a custom error message when `key` is not in the map.
 *
 * CAUTION: This function is deprecated because it requires allocating memory for the error
 * message unnecessarily. For custom revert reasons use {tryGet}.
 */
 function get(
 UintToUintMap storage map,
 uint256 key,
 string memory errorMessage
 ) internal view returns (uint256) {
 return uint256(get(map._inner, bytes32(key), errorMessage));
 }

 // UintToAddressMap

 struct UintToAddressMap {
 Bytes32ToBytes32Map _inner;
 }

 /**
 * @dev Adds a key-value pair to a map, or updates the value for an existing
 * key. O(1).
 *
 * Returns true if the key was added to the map, that is if it was not
 * already present.
 */
 function set(
 UintToAddressMap storage map,
 uint256 key,
 address value
 ) internal returns (bool) {
 return set(map._inner, bytes32(key), bytes32(uint256(uint160(value))));
 }

 /**
 * @dev Removes a value from a set. O(1).
 *
 * Returns true if the key was removed from the map, that is if it was present.
 */
 function remove(UintToAddressMap storage map, uint256 key) internal returns (bool) {
 return remove(map._inner, bytes32(key));
 }

 /**
 * @dev Returns true if the key is in the map. O(1).
 */
 function contains(UintToAddressMap storage map, uint256 key) internal view returns (bool) {
 return contains(map._inner, bytes32(key));
 }

 /**
 * @dev Returns the number of elements in the map. O(1).
 */
 function length(UintToAddressMap storage map) internal view returns (uint256) {
 return length(map._inner);
 }

 /**
 * @dev Returns the element stored at position `index` in the set. O(1).
 * Note that there are no guarantees on the ordering of values inside the
 * array, and it may change when more values are added or removed.
 *
 * Requirements:
 *
 * - `index` must be strictly less than {length}.
 */
 function at(UintToAddressMap storage map, uint256 index) internal view returns (uint256, address) {
 (bytes32 key, bytes32 value) = at(map._inner, index);
 return (uint256(key), address(uint160(uint256(value))));
 }

 /**
 * @dev Tries to returns the value associated with `key`. O(1).
 * Does not revert if `key` is not in the map.
 *
 * _Available since v3.4._
 */
 function tryGet(UintToAddressMap storage map, uint256 key) internal view returns (bool, address) {
 (bool success, bytes32 value) = tryGet(map._inner, bytes32(key));
 return (success, address(uint160(uint256(value))));
 }

 /**
 * @dev Returns the value associated with `key`. O(1).
 *
 * Requirements:
 *
 * - `key` must be in the map.
 */
 function get(UintToAddressMap storage map, uint256 key) internal view returns (address) {
 return address(uint160(uint256(get(map._inner, bytes32(key)))));
 }

 /**
 * @dev Same as {get}, with a custom error message when `key` is not in the map.
 *
 * CAUTION: This function is deprecated because it requires allocating memory for the error
 * message unnecessarily. For custom revert reasons use {tryGet}.
 */
 function get(
 UintToAddressMap storage map,
 uint256 key,
 string memory errorMessage
 ) internal view returns (address) {
 return address(uint160(uint256(get(map._inner, bytes32(key), errorMessage))));
 }

 // AddressToUintMap

 struct AddressToUintMap {
 Bytes32ToBytes32Map _inner;
 }

 /**
 * @dev Adds a key-value pair to a map, or updates the value for an existing
 * key. O(1).
 *
 * Returns true if the key was added to the map, that is if it was not
 * already present.
 */
 function set(
 AddressToUintMap storage map,
 address key,
 uint256 value
 ) internal returns (bool) {
 return set(map._inner, bytes32(uint256(uint160(key))), bytes32(value));
 }

 /**
 * @dev Removes a value from a set. O(1).
 *
 * Returns true if the key was removed from the map, that is if it was present.
 */
 function remove(AddressToUintMap storage map, address key) internal returns (bool) {
 return remove(map._inner, bytes32(uint256(uint160(key))));
 }

 /**
 * @dev Returns true if the key is in the map. O(1).
 */
 function contains(AddressToUintMap storage map, address key) internal view returns (bool) {
 return contains(map._inner, bytes32(uint256(uint160(key))));
 }

 /**
 * @dev Returns the number of elements in the map. O(1).
 */
 function length(AddressToUintMap storage map) internal view returns (uint256) {
 return length(map._inner);
 }

 /**
 * @dev Returns the element stored at position `index` in the set. O(1).
 * Note that there are no guarantees on the ordering of values inside the
 * array, and it may change when more values are added or removed.
 *
 * Requirements:
 *
 * - `index` must be strictly less than {length}.
 */
 function at(AddressToUintMap storage map, uint256 index) internal view returns (address, uint256) {
 (bytes32 key, bytes32 value) = at(map._inner, index);
 return (address(uint160(uint256(key))), uint256(value));
 }

 /**
 * @dev Tries to returns the value associated with `key`. O(1).
 * Does not revert if `key` is not in the map.
 */
 function tryGet(AddressToUintMap storage map, address key) internal view returns (bool, uint256) {
 (bool success, bytes32 value) = tryGet(map._inner, bytes32(uint256(uint160(key))));
 return (success, uint256(value));
 }

 /**
 * @dev Returns the value associated with `key`. O(1).
 *
 * Requirements:
 *
 * - `key` must be in the map.
 */
 function get(AddressToUintMap storage map, address key) internal view returns (uint256) {
 return uint256(get(map._inner, bytes32(uint256(uint160(key)))));
 }

 /**
 * @dev Same as {get}, with a custom error message when `key` is not in the map.
 *
 * CAUTION: This function is deprecated because it requires allocating memory for the error
 * message unnecessarily. For custom revert reasons use {tryGet}.
 */
 function get(
 AddressToUintMap storage map,
 address key,
 string memory errorMessage
 ) internal view returns (uint256) {
 return uint256(get(map._inner, bytes32(uint256(uint160(key))), errorMessage));
 }

 // Bytes32ToUintMap

 struct Bytes32ToUintMap {
 Bytes32ToBytes32Map _inner;
 }

 /**
 * @dev Adds a key-value pair to a map, or updates the value for an existing
 * key. O(1).
 *
 * Returns true if the key was added to the map, that is if it was not
 * already present.
 */
 function set(
 Bytes32ToUintMap storage map,
 bytes32 key,
 uint256 value
 ) internal returns (bool) {
 return set(map._inner, key, bytes32(value));
 }

 /**
 * @dev Removes a value from a set. O(1).
 *
 * Returns true if the key was removed from the map, that is if it was present.
 */
 function remove(Bytes32ToUintMap storage map, bytes32 key) internal returns (bool) {
 return remove(map._inner, key);
 }

 /**
 * @dev Returns true if the key is in the map. O(1).
 */
 function contains(Bytes32ToUintMap storage map, bytes32 key) internal view returns (bool) {
 return contains(map._inner, key);
 }

 /**
 * @dev Returns the number of elements in the map. O(1).
 */
 function length(Bytes32ToUintMap storage map) internal view returns (uint256) {
 return length(map._inner);
 }

 /**
 * @dev Returns the element stored at position `index` in the set. O(1).
 * Note that there are no guarantees on the ordering of values inside the
 * array, and it may change when more values are added or removed.
 *
 * Requirements:
 *
 * - `index` must be strictly less than {length}.
 */
 function at(Bytes32ToUintMap storage map, uint256 index) internal view returns (bytes32, uint256) {
 (bytes32 key, bytes32 value) = at(map._inner, index);
 return (key, uint256(value));
 }

 /**
 * @dev Tries to returns the value associated with `key`. O(1).
 * Does not revert if `key` is not in the map.
 */
 function tryGet(Bytes32ToUintMap storage map, bytes32 key) internal view returns (bool, uint256) {
 (bool success, bytes32 value) = tryGet(map._inner, key);
 return (success, uint256(value));
 }

 /**
 * @dev Returns the value associated with `key`. O(1).
 *
 * Requirements:
 *
 * - `key` must be in the map.
 */
 function get(Bytes32ToUintMap storage map, bytes32 key) internal view returns (uint256) {
 return uint256(get(map._inner, key));
 }

 /**
 * @dev Same as {get}, with a custom error message when `key` is not in the map.
 *
 * CAUTION: This function is deprecated because it requires allocating memory for the error
 * message unnecessarily. For custom revert reasons use {tryGet}.
 */
 function get(
 Bytes32ToUintMap storage map,
 bytes32 key,
 string memory errorMessage
 ) internal view returns (uint256) {
 return uint256(get(map._inner, key, errorMessage));
 }
}

// File: @openzeppelin/contracts/utils/Strings.sol


// OpenZeppelin Contracts (last updated v4.7.0) (utils/Strings.sol)

pragma solidity ^0.8.0;

/**
 * @dev String operations.
 */
library Strings {
 bytes16 private constant _HEX_SYMBOLS = "0123456789abcdef";
 uint8 private constant _ADDRESS_LENGTH = 20;

 /**
 * @dev Converts a `uint256` to its ASCII `string` decimal representation.
 */
 function toString(uint256 value) internal pure returns (string memory) {
 // Inspired by OraclizeAPI9s implementation - MIT licence
 // https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol

 if (value == 0) {
 return "0";
 }
 uint256 temp = value;
 uint256 digits;
 while (temp != 0) {
 digits++;
 temp /= 10;
 }
 bytes memory buffer = new bytes(digits);
 while (value != 0) {
 digits -= 1;
 buffer[digits] = bytes1(uint8(48 + uint256(value % 10)));
 value /= 10;
 }
 return string(buffer);
 }

 /**
 * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
 */
 function toHexString(uint256 value) internal pure returns (string memory) {
 if (value == 0) {
 return "0x00";
 }
 uint256 temp = value;
 uint256 length = 0;
 while (temp != 0) {
 length++;
 temp >>= 8;
 }
 return toHexString(value, length);
 }

 /**
 * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
 */
 function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
 bytes memory buffer = new bytes(2 * length + 2);
 buffer[0] = "0";
 buffer[1] = "x";
 for (uint256 i = 2 * length + 1; i > 1; --i) {
 buffer[i] = _HEX_SYMBOLS[value & 0xf];
 value >>= 4;
 }
 require(value == 0, "Strings: hex length insufficient");
 return string(buffer);
 }

 /**
 * @dev Converts an `address` with fixed length of 20 bytes to its not checksummed ASCII `string` hexadecimal representation.
 */
 function toHexString(address addr) internal pure returns (string memory) {
 return toHexString(uint256(uint160(addr)), _ADDRESS_LENGTH);
 }
}

// File: @openzeppelin/contracts/utils/Context.sol


// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

pragma solidity ^0.8.0;

/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
 function _msgSender() internal view virtual returns (address) {
 return msg.sender;
 }

 function _msgData() internal view virtual returns (bytes calldata) {
 return msg.data;
 }
}

// File: @openzeppelin/contracts/access/Ownable.sol


// OpenZeppelin Contracts (last updated v4.7.0) (access/Ownable.sol)

pragma solidity ^0.8.0;


/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
 address private _owner;

 event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

 /**
 * @dev Initializes the contract setting the deployer as the initial owner.
 */
 constructor() {
 _transferOwnership(_msgSender());
 }

 /**
 * @dev Throws if called by any account other than the owner.
 */
 modifier onlyOwner() {
 _checkOwner();
 _;
 }

 /**
 * @dev Returns the address of the current owner.
 */
 function owner() public view virtual returns (address) {
 return _owner;
 }

 /**
 * @dev Throws if the sender is not the owner.
 */
 function _checkOwner() internal view virtual {
 require(owner() == _msgSender(), "Ownable: caller is not the owner");
 }

 /**
 * @dev Leaves the contract without owner. It will not be possible to call
 * `onlyOwner` functions anymore. Can only be called by the current owner.
 *
 * NOTE: Renouncing ownership will leave the contract without an owner,
 * thereby removing any functionality that is only available to the owner.
 */
 function renounceOwnership() public virtual onlyOwner {
 _transferOwnership(address(0));
 }

 /**
 * @dev Transfers ownership of the contract to a new account (`newOwner`).
 * Can only be called by the current owner.
 */
 function transferOwnership(address newOwner) public virtual onlyOwner {
 require(newOwner != address(0), "Ownable: new owner is the zero address");
 _transferOwnership(newOwner);
 }

 /**
 * @dev Transfers ownership of the contract to a new account (`newOwner`).
 * Internal function without access restriction.
 */
 function _transferOwnership(address newOwner) internal virtual {
 address oldOwner = _owner;
 _owner = newOwner;
 emit OwnershipTransferred(oldOwner, newOwner);
 }
}

// File: @openzeppelin/contracts/utils/Address.sol


// OpenZeppelin Contracts (last updated v4.7.0) (utils/Address.sol)

pragma solidity ^0.8.1;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
 /**
 * @dev Returns true if `account` is a contract.
 *
 * [IMPORTANT]
 * ====
 * It is unsafe to assume that an address for which this function returns
 * false is an externally-owned account (EOA) and not a contract.
 *
 * Among others, `isContract` will return false for the following
 * types of addresses:
 *
 * - an externally-owned account
 * - a contract in construction
 * - an address where a contract will be created
 * - an address where a contract lived, but was destroyed
 * ====
 *
 * [IMPORTANT]
 * ====
 * You shouldn9t rely on `isContract` to protect against flash loan attacks!
 *
 * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
 * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
 * constructor.
 * ====
 */
 function isContract(address account) internal view returns (bool) {
 // This method relies on extcodesize/address.code.length, which returns 0
 // for contracts in construction, since the code is only stored at the end
 // of the constructor execution.

 return account.code.length > 0;
 }

 /**
 * @dev Replacement for Solidity9s `transfer`: sends `amount` wei to
 * `recipient`, forwarding all available gas and reverting on errors.
 *
 * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
 * of certain opcodes, possibly making contracts go over the 2300 gas limit
 * imposed by `transfer`, making them unable to receive funds via
 * `transfer`. {sendValue} removes this limitation.
 *
 * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
 *
 * IMPORTANT: because control is transferred to `recipient`, care must be
 * taken to not create reentrancy vulnerabilities. Consider using
 * {ReentrancyGuard} or the
 * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
 */
 function sendValue(address payable recipient, uint256 amount) internal {
 require(address(this).balance >= amount, "Address: insufficient balance");

 (bool success, ) = recipient.call{value: amount}("");
 require(success, "Address: unable to send value, recipient may have reverted");
 }

 /**
 * @dev Performs a Solidity function call using a low level `call`. A
 * plain `call` is an unsafe replacement for a function call: use this
 * function instead.
 *
 * If `target` reverts with a revert reason, it is bubbled up by this
 * function (like regular Solidity function calls).
 *
 * Returns the raw returned data. To convert to the expected return value,
 * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
 *
 * Requirements:
 *
 * - `target` must be a contract.
 * - calling `target` with `data` must not revert.
 *
 * _Available since v3.1._
 */
 function functionCall(address target, bytes memory data) internal returns (bytes memory) {
 return functionCall(target, data, "Address: low-level call failed");
 }

 /**
 * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
 * `errorMessage` as a fallback revert reason when `target` reverts.
 *
 * _Available since v3.1._
 */
 function functionCall(
 address target,
 bytes memory data,
 string memory errorMessage
 ) internal returns (bytes memory) {
 return functionCallWithValue(target, data, 0, errorMessage);
 }

 /**
 * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
 * but also transferring `value` wei to `target`.
 *
 * Requirements:
 *
 * - the calling contract must have an ETH balance of at least `value`.
 * - the called Solidity function must be `payable`.
 *
 * _Available since v3.1._
 */
 function functionCallWithValue(
 address target,
 bytes memory data,
 uint256 value
 ) internal returns (bytes memory) {
 return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
 }

 /**
 * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
 * with `errorMessage` as a fallback revert reason when `target` reverts.
 *
 * _Available since v3.1._
 */
 function functionCallWithValue(
 address target,
 bytes memory data,
 uint256 value,
 string memory errorMessage
 ) internal returns (bytes memory) {
 require(address(this).balance >= value, "Address: insufficient balance for call");
 require(isContract(target), "Address: call to non-contract");

 (bool success, bytes memory returndata) = target.call{value: value}(data);
 return verifyCallResult(success, returndata, errorMessage);
 }

 /**
 * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
 * but performing a static call.
 *
 * _Available since v3.3._
 */
 function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
 return functionStaticCall(target, data, "Address: low-level static call failed");
 }

 /**
 * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
 * but performing a static call.
 *
 * _Available since v3.3._
 */
 function functionStaticCall(
 address target,
 bytes memory data,
 string memory errorMessage
 ) internal view returns (bytes memory) {
 require(isContract(target), "Address: static call to non-contract");

 (bool success, bytes memory returndata) = target.staticcall(data);
 return verifyCallResult(success, returndata, errorMessage);
 }

 /**
 * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
 * but performing a delegate call.
 *
 * _Available since v3.4._
 */
 function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
 return functionDelegateCall(target, data, "Address: low-level delegate call failed");
 }

 /**
 * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
 * but performing a delegate call.
 *
 * _Available since v3.4._
 */
 function functionDelegateCall(
 address target,
 bytes memory data,
 string memory errorMessage
 ) internal returns (bytes memory) {
 require(isContract(target), "Address: delegate call to non-contract");

 (bool success, bytes memory returndata) = target.delegatecall(data);
 return verifyCallResult(success, returndata, errorMessage);
 }

 /**
 * @dev Tool to verifies that a low level call was successful, and revert if it wasn9t, either by bubbling the
 * revert reason using the provided one.
 *
 * _Available since v4.3._
 */
 function verifyCallResult(
 bool success,
 bytes memory returndata,
 string memory errorMessage
 ) internal pure returns (bytes memory) {
 if (success) {
 return returndata;
 } else {
 // Look for revert reason and bubble it up if present
 if (returndata.length > 0) {
 // The easiest way to bubble the revert reason is using memory via assembly
 /// @solidity memory-safe-assembly
 assembly {
 let returndata_size := mload(returndata)
 revert(add(32, returndata), returndata_size)
 }
 } else {
 revert(errorMessage);
 }
 }
 }
}

// File: @openzeppelin/contracts/token/ERC721/IERC721Receiver.sol


// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC721/IERC721Receiver.sol)

pragma solidity ^0.8.0;

/**
 * @title ERC721 token receiver interface
 * @dev Interface for any contract that wants to support safeTransfers
 * from ERC721 asset contracts.
 */
interface IERC721Receiver {
 /**
 * @dev Whenever an {IERC721} `tokenId` token is transferred to this contract via {IERC721-safeTransferFrom}
 * by `operator` from `from`, this function is called.
 *
 * It must return its Solidity selector to confirm the token transfer.
 * If any other value is returned or the interface is not implemented by the recipient, the transfer will be reverted.
 *
 * The selector can be obtained in Solidity with `IERC721Receiver.onERC721Received.selector`.
 */
 function onERC721Received(
 address operator,
 address from,
 uint256 tokenId,
 bytes calldata data
 ) external returns (bytes4);
}

// File: @openzeppelin/contracts/utils/introspection/IERC165.sol


// OpenZeppelin Contracts v4.4.1 (utils/introspection/IERC165.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC165 standard, as defined in the
 * https://eips.ethereum.org/EIPS/eip-165[EIP].
 *
 * Implementers can declare support of contract interfaces, which can then be
 * queried by others ({ERC165Checker}).
 *
 * For an implementation, see {ERC165}.
 */
interface IERC165 {
 /**
 * @dev Returns true if this contract implements the interface defined by
 * `interfaceId`. See the corresponding
 * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
 * to learn more about how these ids are created.
 *
 * This function call must use less than 30 000 gas.
 */
 function supportsInterface(bytes4 interfaceId) external view returns (bool);
}

// File: @openzeppelin/contracts/utils/introspection/ERC165.sol


// OpenZeppelin Contracts v4.4.1 (utils/introspection/ERC165.sol)

pragma solidity ^0.8.0;


/**
 * @dev Implementation of the {IERC165} interface.
 *
 * Contracts that want to implement ERC165 should inherit from this contract and override {supportsInterface} to check
 * for the additional interface id that will be supported. For example:
 *
 * ```solidity
 * function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
 * return interfaceId == type(MyInterface).interfaceId || super.supportsInterface(interfaceId);
 * }
 * ```
 *
 * Alternatively, {ERC165Storage} provides an easier to use but more expensive implementation.
 */
abstract contract ERC165 is IERC165 {
 /**
 * @dev See {IERC165-supportsInterface}.
 */
 function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
 return interfaceId == type(IERC165).interfaceId;
 }
}

// File: @openzeppelin/contracts/token/ERC721/IERC721.sol


// OpenZeppelin Contracts (last updated v4.7.0) (token/ERC721/IERC721.sol)

pragma solidity ^0.8.0;


/**
 * @dev Required interface of an ERC721 compliant contract.
 */
interface IERC721 is IERC165 {
 /**
 * @dev Emitted when `tokenId` token is transferred from `from` to `to`.
 */
 event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);

 /**
 * @dev Emitted when `owner` enables `approved` to manage the `tokenId` token.
 */
 event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);

 /**
 * @dev Emitted when `owner` enables or disables (`approved`) `operator` to manage all of its assets.
 */
 event ApprovalForAll(address indexed owner, address indexed operator, bool approved);

 /**
 * @dev Returns the number of tokens in ``owner``9s account.
 */
 function balanceOf(address owner) external view returns (uint256 balance);

 /**
 * @dev Returns the owner of the `tokenId` token.
 *
 * Requirements:
 *
 * - `tokenId` must exist.
 */
 function ownerOf(uint256 tokenId) external view returns (address owner);

 /**
 * @dev Safely transfers `tokenId` token from `from` to `to`.
 *
 * Requirements:
 *
 * - `from` cannot be the zero address.
 * - `to` cannot be the zero address.
 * - `tokenId` token must exist and be owned by `from`.
 * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
 * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
 *
 * Emits a {Transfer} event.
 */
 function safeTransferFrom(
 address from,
 address to,
 uint256 tokenId,
 bytes calldata data
 ) external;

 /**
 * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
 * are aware of the ERC721 protocol to prevent tokens from being forever locked.
 *
 * Requirements:
 *
 * - `from` cannot be the zero address.
 * - `to` cannot be the zero address.
 * - `tokenId` token must exist and be owned by `from`.
 * - If the caller is not `from`, it must have been allowed to move this token by either {approve} or {setApprovalForAll}.
 * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
 *
 * Emits a {Transfer} event.
 */
 function safeTransferFrom(
 address from,
 address to,
 uint256 tokenId
 ) external;

 /**
 * @dev Transfers `tokenId` token from `from` to `to`.
 *
 * WARNING: Usage of this method is discouraged, use {safeTransferFrom} whenever possible.
 *
 * Requirements:
 *
 * - `from` cannot be the zero address.
 * - `to` cannot be the zero address.
 * - `tokenId` token must be owned by `from`.
 * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
 *
 * Emits a {Transfer} event.
 */
 function transferFrom(
 address from,
 address to,
 uint256 tokenId
 ) external;

 /**
 * @dev Gives permission to `to` to transfer `tokenId` token to another account.
 * The approval is cleared when the token is transferred.
 *
 * Only a single account can be approved at a time, so approving the zero address clears previous approvals.
 *
 * Requirements:
 *
 * - The caller must own the token or be an approved operator.
 * - `tokenId` must exist.
 *
 * Emits an {Approval} event.
 */
 function approve(address to, uint256 tokenId) external;

 /**
 * @dev Approve or remove `operator` as an operator for the caller.
 * Operators can call {transferFrom} or {safeTransferFrom} for any token owned by the caller.
 *
 * Requirements:
 *
 * - The `operator` cannot be the caller.
 *
 * Emits an {ApprovalForAll} event.
 */
 function setApprovalForAll(address operator, bool _approved) external;

 /**
 * @dev Returns the account approved for `tokenId` token.
 *
 * Requirements:
 *
 * - `tokenId` must exist.
 */
 function getApproved(uint256 tokenId) external view returns (address operator);

 /**
 * @dev Returns if the `operator` is allowed to manage all of the assets of `owner`.
 *
 * See {setApprovalForAll}
 */
 function isApprovedForAll(address owner, address operator) external view returns (bool);
}

// File: @openzeppelin/contracts/token/ERC721/extensions/IERC721Enumerable.sol


// OpenZeppelin Contracts (last updated v4.5.0) (token/ERC721/extensions/IERC721Enumerable.sol)

pragma solidity ^0.8.0;


/**
 * @title ERC-721 Non-Fungible Token Standard, optional enumeration extension
 * @dev See https://eips.ethereum.org/EIPS/eip-721
 */
interface IERC721Enumerable is IERC721 {
 /**
 * @dev Returns the total amount of tokens stored by the contract.
 */
 function totalSupply() external view returns (uint256);

 /**
 * @dev Returns a token ID owned by `owner` at a given `index` of its token list.
 * Use along with {balanceOf} to enumerate all of ``owner``9s tokens.
 */
 function tokenOfOwnerByIndex(address owner, uint256 index) external view returns (uint256);

 /**
 * @dev Returns a token ID at a given `index` of all the tokens stored by the contract.
 * Use along with {totalSupply} to enumerate all tokens.
 */
 function tokenByIndex(uint256 index) external view returns (uint256);
}

// File: @openzeppelin/contracts/token/ERC721/extensions/IERC721Metadata.sol


// OpenZeppelin Contracts v4.4.1 (token/ERC721/extensions/IERC721Metadata.sol)

pragma solidity ^0.8.0;


/**
 * @title ERC-721 Non-Fungible Token Standard, optional metadata extension
 * @dev See https://eips.ethereum.org/EIPS/eip-721
 */
interface IERC721Metadata is IERC721 {
 /**
 * @dev Returns the token collection name.
 */
 function name() external view returns (string memory);

 /**
 * @dev Returns the token collection symbol.
 */
 function symbol() external view returns (string memory);

 /**
 * @dev Returns the Uniform Resource Identifier (URI) for `tokenId` token.
 */
 function tokenURI(uint256 tokenId) external view returns (string memory);
}

// File: @openzeppelin/contracts/token/ERC721/ERC721.sol


// OpenZeppelin Contracts (last updated v4.7.0) (token/ERC721/ERC721.sol)

pragma solidity ^0.8.0;








/**
 * @dev Implementation of https://eips.ethereum.org/EIPS/eip-721[ERC721] Non-Fungible Token Standard, including
 * the Metadata extension, but not including the Enumerable extension, which is available separately as
 * {ERC721Enumerable}.
 */
contract ERC721 is Context, ERC165, IERC721, IERC721Metadata {
 using Address for address;
 using Strings for uint256;

 // Token name
 string private _name;

 // Token symbol
 string private _symbol;

 // Mapping from token ID to owner address
 mapping(uint256 => address) private _owners;

 // Mapping owner address to token count
 mapping(address => uint256) private _balances;

 // Mapping from token ID to approved address
 mapping(uint256 => address) private _tokenApprovals;

 // Mapping from owner to operator approvals
 mapping(address => mapping(address => bool)) private _operatorApprovals;

 /**
 * @dev Initializes the contract by setting a `name` and a `symbol` to the token collection.
 */
 constructor(string memory name_, string memory symbol_) {
 _name = name_;
 _symbol = symbol_;
 }

 /**
 * @dev See {IERC165-supportsInterface}.
 */
 function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns (bool) {
 return
 interfaceId == type(IERC721).interfaceId ||
 interfaceId == type(IERC721Metadata).interfaceId ||
 super.supportsInterface(interfaceId);
 }

 /**
 * @dev See {IERC721-balanceOf}.
 */
 function balanceOf(address owner) public view virtual override returns (uint256) {
 require(owner != address(0), "ERC721: address zero is not a valid owner");
 return _balances[owner];
 }

 /**
 * @dev See {IERC721-ownerOf}.
 */
 function ownerOf(uint256 tokenId) public view virtual override returns (address) {
 address owner = _owners[tokenId];
 require(owner != address(0), "ERC721: invalid token ID");
 return owner;
 }

 /**
 * @dev See {IERC721Metadata-name}.
 */
 function name() public view virtual override returns (string memory) {
 return _name;
 }

 /**
 * @dev See {IERC721Metadata-symbol}.
 */
 function symbol() public view virtual override returns (string memory) {
 return _symbol;
 }

 /**
 * @dev See {IERC721Metadata-tokenURI}.
 */
 function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
 _requireMinted(tokenId);

 string memory baseURI = _baseURI();
 return bytes(baseURI).length > 0 ? string(abi.encodePacked(baseURI, tokenId.toString())) : "";
 }

 /**
 * @dev Base URI for computing {tokenURI}. If set, the resulting URI for each
 * token will be the concatenation of the `baseURI` and the `tokenId`. Empty
 * by default, can be overridden in child contracts.
 */
 function _baseURI() internal view virtual returns (string memory) {
 return "";
 }

 /**
 * @dev See {IERC721-approve}.
 */
 function approve(address to, uint256 tokenId) public virtual override {
 address owner = ERC721.ownerOf(tokenId);
 require(to != owner, "ERC721: approval to current owner");

 require(
 _msgSender() == owner || isApprovedForAll(owner, _msgSender()),
 "ERC721: approve caller is not token owner nor approved for all"
 );

 _approve(to, tokenId);
 }

 /**
 * @dev See {IERC721-getApproved}.
 */
 function getApproved(uint256 tokenId) public view virtual override returns (address) {
 _requireMinted(tokenId);

 return _tokenApprovals[tokenId];
 }

 /**
 * @dev See {IERC721-setApprovalForAll}.
 */
 function setApprovalForAll(address operator, bool approved) public virtual override {
 _setApprovalForAll(_msgSender(), operator, approved);
 }

 /**
 * @dev See {IERC721-isApprovedForAll}.
 */
 function isApprovedForAll(address owner, address operator) public view virtual override returns (bool) {
 return _operatorApprovals[owner][operator];
 }

 /**
 * @dev See {IERC721-transferFrom}.
 */
 function transferFrom(
 address from,
 address to,
 uint256 tokenId
 ) public virtual override {
 //solhint-disable-next-line max-line-length
 require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: caller is not token owner nor approved");

 _transfer(from, to, tokenId);
 }

 /**
 * @dev See {IERC721-safeTransferFrom}.
 */
 function safeTransferFrom(
 address from,
 address to,
 uint256 tokenId
 ) public virtual override {
 safeTransferFrom(from, to, tokenId, "");
 }

 /**
 * @dev See {IERC721-safeTransferFrom}.
 */
 function safeTransferFrom(
 address from,
 address to,
 uint256 tokenId,
 bytes memory data
 ) public virtual override {
 require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: caller is not token owner nor approved");
 _safeTransfer(from, to, tokenId, data);
 }

 /**
 * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
 * are aware of the ERC721 protocol to prevent tokens from being forever locked.
 *
 * `data` is additional data, it has no specified format and it is sent in call to `to`.
 *
 * This internal function is equivalent to {safeTransferFrom}, and can be used to e.g.
 * implement alternative mechanisms to perform token transfer, such as signature-based.
 *
 * Requirements:
 *
 * - `from` cannot be the zero address.
 * - `to` cannot be the zero address.
 * - `tokenId` token must exist and be owned by `from`.
 * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
 *
 * Emits a {Transfer} event.
 */
 function _safeTransfer(
 address from,
 address to,
 uint256 tokenId,
 bytes memory data
 ) internal virtual {
 _transfer(from, to, tokenId);
 require(_checkOnERC721Received(from, to, tokenId, data), "ERC721: transfer to non ERC721Receiver implementer");
 }

 /**
 * @dev Returns whether `tokenId` exists.
 *
 * Tokens can be managed by their owner or approved accounts via {approve} or {setApprovalForAll}.
 *
 * Tokens start existing when they are minted (`_mint`),
 * and stop existing when they are burned (`_burn`).
 */
 function _exists(uint256 tokenId) internal view virtual returns (bool) {
 return _owners[tokenId] != address(0);
 }

 /**
 * @dev Returns whether `spender` is allowed to manage `tokenId`.
 *
 * Requirements:
 *
 * - `tokenId` must exist.
 */
 function _isApprovedOrOwner(address spender, uint256 tokenId) internal view virtual returns (bool) {
 address owner = ERC721.ownerOf(tokenId);
 return (spender == owner || isApprovedForAll(owner, spender) || getApproved(tokenId) == spender);
 }

 /**
 * @dev Safely mints `tokenId` and transfers it to `to`.
 *
 * Requirements:
 *
 * - `tokenId` must not exist.
 * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
 *
 * Emits a {Transfer} event.
 */
 function _safeMint(address to, uint256 tokenId) internal virtual {
 _safeMint(to, tokenId, "");
 }

 /**
 * @dev Same as {xref-ERC721-_safeMint-address-uint256-}[`_safeMint`], with an additional `data` parameter which is
 * forwarded in {IERC721Receiver-onERC721Received} to contract recipients.
 */
 function _safeMint(
 address to,
 uint256 tokenId,
 bytes memory data
 ) internal virtual {
 _mint(to, tokenId);
 require(
 _checkOnERC721Received(address(0), to, tokenId, data),
 "ERC721: transfer to non ERC721Receiver implementer"
 );
 }

 /**
 * @dev Mints `tokenId` and transfers it to `to`.
 *
 * WARNING: Usage of this method is discouraged, use {_safeMint} whenever possible
 *
 * Requirements:
 *
 * - `tokenId` must not exist.
 * - `to` cannot be the zero address.
 *
 * Emits a {Transfer} event.
 */
 function _mint(address to, uint256 tokenId) internal virtual {
 require(to != address(0), "ERC721: mint to the zero address");
 require(!_exists(tokenId), "ERC721: token already minted");

 _beforeTokenTransfer(address(0), to, tokenId);

 _balances[to] += 1;
 _owners[tokenId] = to;

 emit Transfer(address(0), to, tokenId);

 _afterTokenTransfer(address(0), to, tokenId);
 }

 /**
 * @dev Destroys `tokenId`.
 * The approval is cleared when the token is burned.
 *
 * Requirements:
 *
 * - `tokenId` must exist.
 *
 * Emits a {Transfer} event.
 */
 function _burn(uint256 tokenId) internal virtual {
 address owner = ERC721.ownerOf(tokenId);

 _beforeTokenTransfer(owner, address(0), tokenId);

 // Clear approvals
 _approve(address(0), tokenId);

 _balances[owner] -= 1;
 delete _owners[tokenId];

 emit Transfer(owner, address(0), tokenId);

 _afterTokenTransfer(owner, address(0), tokenId);
 }

 /**
 * @dev Transfers `tokenId` from `from` to `to`.
 * As opposed to {transferFrom}, this imposes no restrictions on msg.sender.
 *
 * Requirements:
 *
 * - `to` cannot be the zero address.
 * - `tokenId` token must be owned by `from`.
 *
 * Emits a {Transfer} event.
 */
 function _transfer(
 address from,
 address to,
 uint256 tokenId
 ) internal virtual {
 require(ERC721.ownerOf(tokenId) == from, "ERC721: transfer from incorrect owner");
 require(to != address(0), "ERC721: transfer to the zero address");

 _beforeTokenTransfer(from, to, tokenId);

 // Clear approvals from the previous owner
 _approve(address(0), tokenId);

 _balances[from] -= 1;
 _balances[to] += 1;
 _owners[tokenId] = to;

 emit Transfer(from, to, tokenId);

 _afterTokenTransfer(from, to, tokenId);
 }

 /**
 * @dev Approve `to` to operate on `tokenId`
 *
 * Emits an {Approval} event.
 */
 function _approve(address to, uint256 tokenId) internal virtual {
 _tokenApprovals[tokenId] = to;
 emit Approval(ERC721.ownerOf(tokenId), to, tokenId);
 }

 /**
 * @dev Approve `operator` to operate on all of `owner` tokens
 *
 * Emits an {ApprovalForAll} event.
 */
 function _setApprovalForAll(
 address owner,
 address operator,
 bool approved
 ) internal virtual {
 require(owner != operator, "ERC721: approve to caller");
 _operatorApprovals[owner][operator] = approved;
 emit ApprovalForAll(owner, operator, approved);
 }

 /**
 * @dev Reverts if the `tokenId` has not been minted yet.
 */
 function _requireMinted(uint256 tokenId) internal view virtual {
 require(_exists(tokenId), "ERC721: invalid token ID");
 }

 /**
 * @dev Internal function to invoke {IERC721Receiver-onERC721Received} on a target address.
 * The call is not executed if the target address is not a contract.
 *
 * @param from address representing the previous owner of the given token ID
 * @param to target address that will receive the tokens
 * @param tokenId uint256 ID of the token to be transferred
 * @param data bytes optional data to send along with the call
 * @return bool whether the call correctly returned the expected magic value
 */
 function _checkOnERC721Received(
 address from,
 address to,
 uint256 tokenId,
 bytes memory data
 ) private returns (bool) {
 if (to.isContract()) {
 try IERC721Receiver(to).onERC721Received(_msgSender(), from, tokenId, data) returns (bytes4 retval) {
 return retval == IERC721Receiver.onERC721Received.selector;
 } catch (bytes memory reason) {
 if (reason.length == 0) {
 revert("ERC721: transfer to non ERC721Receiver implementer");
 } else {
 /// @solidity memory-safe-assembly
 assembly {
 revert(add(32, reason), mload(reason))
 }
 }
 }
 } else {
 return true;
 }
 }

 /**
 * @dev Hook that is called before any token transfer. This includes minting
 * and burning.
 *
 * Calling conditions:
 *
 * - When `from` and `to` are both non-zero, ``from``9s `tokenId` will be
 * transferred to `to`.
 * - When `from` is zero, `tokenId` will be minted for `to`.
 * - When `to` is zero, ``from``9s `tokenId` will be burned.
 * - `from` and `to` are never both zero.
 *
 * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
 */
 function _beforeTokenTransfer(
 address from,
 address to,
 uint256 tokenId
 ) internal virtual {}

 /**
 * @dev Hook that is called after any transfer of tokens. This includes
 * minting and burning.
 *
 * Calling conditions:
 *
 * - when `from` and `to` are both non-zero.
 * - `from` and `to` are never both zero.
 *
 * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
 */
 function _afterTokenTransfer(
 address from,
 address to,
 uint256 tokenId
 ) internal virtual {}
}

// File: @openzeppelin/contracts/token/ERC721/extensions/ERC721Enumerable.sol


// OpenZeppelin Contracts v4.4.1 (token/ERC721/extensions/ERC721Enumerable.sol)

pragma solidity ^0.8.0;



/**
 * @dev This implements an optional extension of {ERC721} defined in the EIP that adds
 * enumerability of all the token ids in the contract as well as all token ids owned by each
 * account.
 */
abstract contract ERC721Enumerable is ERC721, IERC721Enumerable {
 // Mapping from owner to list of owned token IDs
 mapping(address => mapping(uint256 => uint256)) private _ownedTokens;

 // Mapping from token ID to index of the owner tokens list
 mapping(uint256 => uint256) private _ownedTokensIndex;

 // Array with all token ids, used for enumeration
 uint256[] private _allTokens;

 // Mapping from token id to position in the allTokens array
 mapping(uint256 => uint256) private _allTokensIndex;

 /**
 * @dev See {IERC165-supportsInterface}.
 */
 function supportsInterface(bytes4 interfaceId) public view virtual override(IERC165, ERC721) returns (bool) {
 return interfaceId == type(IERC721Enumerable).interfaceId || super.supportsInterface(interfaceId);
 }

 /**
 * @dev See {IERC721Enumerable-tokenOfOwnerByIndex}.
 */
 function tokenOfOwnerByIndex(address owner, uint256 index) public view virtual override returns (uint256) {
 require(index < ERC721.balanceOf(owner), "ERC721Enumerable: owner index out of bounds");
 return _ownedTokens[owner][index];
 }

 /**
 * @dev See {IERC721Enumerable-totalSupply}.
 */
 function totalSupply() public view virtual override returns (uint256) {
 return _allTokens.length;
 }

 /**
 * @dev See {IERC721Enumerable-tokenByIndex}.
 */
 function tokenByIndex(uint256 index) public view virtual override returns (uint256) {
 require(index < ERC721Enumerable.totalSupply(), "ERC721Enumerable: global index out of bounds");
 return _allTokens[index];
 }

 /**
 * @dev Hook that is called before any token transfer. This includes minting
 * and burning.
 *
 * Calling conditions:
 *
 * - When `from` and `to` are both non-zero, ``from``9s `tokenId` will be
 * transferred to `to`.
 * - When `from` is zero, `tokenId` will be minted for `to`.
 * - When `to` is zero, ``from``9s `tokenId` will be burned.
 * - `from` cannot be the zero address.
 * - `to` cannot be the zero address.
 *
 * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
 */
 function _beforeTokenTransfer(
 address from,
 address to,
 uint256 tokenId
 ) internal virtual override {
 super._beforeTokenTransfer(from, to, tokenId);

 if (from == address(0)) {
 _addTokenToAllTokensEnumeration(tokenId);
 } else if (from != to) {
 _removeTokenFromOwnerEnumeration(from, tokenId);
 }
 if (to == address(0)) {
 _removeTokenFromAllTokensEnumeration(tokenId);
 } else if (to != from) {
 _addTokenToOwnerEnumeration(to, tokenId);
 }
 }

 /**
 * @dev Private function to add a token to this extension9s ownership-tracking data structures.
 * @param to address representing the new owner of the given token ID
 * @param tokenId uint256 ID of the token to be added to the tokens list of the given address
 */
 function _addTokenToOwnerEnumeration(address to, uint256 tokenId) private {
 uint256 length = ERC721.balanceOf(to);
 _ownedTokens[to][length] = tokenId;
 _ownedTokensIndex[tokenId] = length;
 }

 /**
 * @dev Private function to add a token to this extension9s token tracking data structures.
 * @param tokenId uint256 ID of the token to be added to the tokens list
 */
 function _addTokenToAllTokensEnumeration(uint256 tokenId) private {
 _allTokensIndex[tokenId] = _allTokens.length;
 _allTokens.push(tokenId);
 }

 /**
 * @dev Private function to remove a token from this extension9s ownership-tracking data structures. Note that
 * while the token is not assigned a new owner, the `_ownedTokensIndex` mapping is _not_ updated: this allows for
 * gas optimizations e.g. when performing a transfer operation (avoiding double writes).
 * This has O(1) time complexity, but alters the order of the _ownedTokens array.
 * @param from address representing the previous owner of the given token ID
 * @param tokenId uint256 ID of the token to be removed from the tokens list of the given address
 */
 function _removeTokenFromOwnerEnumeration(address from, uint256 tokenId) private {
 // To prevent a gap in from9s tokens array, we store the last token in the index of the token to delete, and
 // then delete the last slot (swap and pop).

 uint256 lastTokenIndex = ERC721.balanceOf(from) - 1;
 uint256 tokenIndex = _ownedTokensIndex[tokenId];

 // When the token to delete is the last token, the swap operation is unnecessary
 if (tokenIndex != lastTokenIndex) {
 uint256 lastTokenId = _ownedTokens[from][lastTokenIndex];

 _ownedTokens[from][tokenIndex] = lastTokenId; // Move the last token to the slot of the to-delete token
 _ownedTokensIndex[lastTokenId] = tokenIndex; // Update the moved token9s index
 }

 // This also deletes the contents at the last position of the array
 delete _ownedTokensIndex[tokenId];
 delete _ownedTokens[from][lastTokenIndex];
 }

 /**
 * @dev Private function to remove a token from this extension9s token tracking data structures.
 * This has O(1) time complexity, but alters the order of the _allTokens array.
 * @param tokenId uint256 ID of the token to be removed from the tokens list
 */
 function _removeTokenFromAllTokensEnumeration(uint256 tokenId) private {
 // To prevent a gap in the tokens array, we store the last token in the index of the token to delete, and
 // then delete the last slot (swap and pop).

 uint256 lastTokenIndex = _allTokens.length - 1;
 uint256 tokenIndex = _allTokensIndex[tokenId];

 // When the token to delete is the last token, the swap operation is unnecessary. However, since this occurs so
 // rarely (when the last minted token is burnt) that we still do the swap here to avoid the gas cost of adding
 // an 9if9 statement (like in _removeTokenFromOwnerEnumeration)
 uint256 lastTokenId = _allTokens[lastTokenIndex];

 _allTokens[tokenIndex] = lastTokenId; // Move the last token to the slot of the to-delete token
 _allTokensIndex[lastTokenId] = tokenIndex; // Update the moved token9s index

 // This also deletes the contents at the last position of the array
 delete _allTokensIndex[tokenId];
 _allTokens.pop();
 }
}

// File: contracts/MultiMintNFT.sol


pragma solidity ^0.8.4;







contract MultiMintNFT is ERC721, ERC721Enumerable, Ownable {
 
 string private _uri;

 bool public isLocked = false;

 modifier isUnlocked () {
 require(isLocked == false, "Contract is locked");
 _;
 }

 event ContractLocked();

 constructor(string memory name, string memory symbol, string memory uri) ERC721(name, symbol) {
 _uri = uri;
 }

 function _baseURI() internal view override returns (string memory) {
 return _uri;
 }

 function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
 require(_exists(tokenId), "URI query for nonexistent token");
 return _baseURI();
 }

 function lockContract() external onlyOwner isUnlocked {
 isLocked = true;
 emit ContractLocked();
 }

 function mintMultiple(address[] calldata to) external onlyOwner isUnlocked {
 require(to.length > 0, "No addresses");

 for (uint i = 0; i < to.length; i++) {
 _safeMint(to[i], totalSupply() + 1);
 }
 }
 
 // The following functions are overrides required by Solidity.
 function _beforeTokenTransfer(address from, address to, uint256 tokenId)
 internal
 override(ERC721, ERC721Enumerable)
 {
 super._beforeTokenTransfer(from, to, tokenId);
 }

 function supportsInterface(bytes4 interfaceId)
 public
 view
 override(ERC721, ERC721Enumerable)
 returns (bool)
 {
 return super.supportsInterface(interfaceId);
 }
}

Contract ABI:

[{"inputs":[{"internalType":"string","name":"name","type":"string"},{"internalType":"string","name":"symbol","type":"string"},{"internalType":"string","name":"uri","type":"string"}],"stateMutability":"nonpayable","type":"constructor"},{"anonymous":false,"inputs":[{"indexed":true,"internalType":"address","name":"owner","type":"address"},{"indexed":true,"internalType":"address","name":"approved","type":"address"},{"indexed":true,"internalType":"uint256","name":"tokenId","type":"uint256"}],"name":"Approval","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"internalType":"address","name":"owner","type":"address"},{"indexed":true,"internalType":"address","name":"operator","type":"address"},{"indexed":false,"internalType":"bool","name":"approved","type":"bool"}],"name":"ApprovalForAll","type":"event"},{"anonymous":false,"inputs":[],"name":"ContractLocked","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"internalType":"address","name":"previousOwner","type":"address"},{"indexed":true,"internalType":"address","name":"newOwner","type":"address"}],"name":"OwnershipTransferred","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"internalType":"address","name":"from","type":"address"},{"indexed":true,"internalType":"address","name":"to","type":"address"},{"indexed":true,"internalType":"uint256","name":"tokenId","type":"uint256"}],"name":"Transfer","type":"event"},{"inputs":[{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"tokenId","type":"uint256"}],"name":"approve","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"owner","type":"address"}],"name":"balanceOf","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"uint256","name":"tokenId","type":"uint256"}],"name":"getApproved","outputs":[{"internalType":"address","name":"","type":"address"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"address","name":"owner","type":"address"},{"internalType":"address","name":"operator","type":"address"}],"name":"isApprovedForAll","outputs":[{"internalType":"bool","name":"","type":"bool"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"isLocked","outputs":[{"internalType":"bool","name":"","type":"bool"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"lockContract","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address[]","name":"to","type":"address[]"}],"name":"mintMultiple","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[],"name":"name","outputs":[{"internalType":"string","name":"","type":"string"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"owner","outputs":[{"internalType":"address","name":"","type":"address"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"uint256","name":"tokenId","type":"uint256"}],"name":"ownerOf","outputs":[{"internalType":"address","name":"","type":"address"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"renounceOwnership","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"from","type":"address"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"tokenId","type":"uint256"}],"name":"safeTransferFrom","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"from","type":"address"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"tokenId","type":"uint256"},{"internalType":"bytes","name":"data","type":"bytes"}],"name":"safeTransferFrom","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"operator","type":"address"},{"internalType":"bool","name":"approved","type":"bool"}],"name":"setApprovalForAll","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"bytes4","name":"interfaceId","type":"bytes4"}],"name":"supportsInterface","outputs":[{"internalType":"bool","name":"","type":"bool"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"symbol","outputs":[{"internalType":"string","name":"","type":"string"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"uint256","name":"index","type":"uint256"}],"name":"tokenByIndex","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"address","name":"owner","type":"address"},{"internalType":"uint256","name":"index","type":"uint256"}],"name":"tokenOfOwnerByIndex","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"uint256","name":"tokenId","type":"uint256"}],"name":"tokenURI","outputs":[{"internalType":"string","name":"","type":"string"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"totalSupply","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"address","name":"from","type":"address"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"tokenId","type":"uint256"}],"name":"transferFrom","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"newOwner","type":"address"}],"name":"transferOwnership","outputs":[],"stateMutability":"nonpayable","type":"function"}]