// File: DRUGON.sol



// File @openzeppelin/contracts/token/ERC20/IERC20.sol@v4.8.3

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
 event Transfer(address indexed from, address indexed to, uint256 value);
 event Approval(address indexed owner, address indexed spender, uint256 value);
 function totalSupply() external view returns (uint256);
 function balanceOf(address account) external view returns (uint256);
 function transfer(address to, uint256 amount) external returns (bool);
 function allowance(address owner, address spender) external view returns (uint256);
 function approve(address spender, uint256 amount) external returns (bool);
 function transferFrom(
 address from,
 address to,
 uint256 amount
 ) external returns (bool);
}
// File @openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol@v4.8.3

// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/IERC20Metadata.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface for the optional metadata functions from the ERC20 standard.
 *
 * _Available since v4.1._
 */
interface IERC20Metadata is IERC20 {
 /**
 * @dev Returns the name of the token.
 */
 function name() external view returns (string memory);

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

 /**
 * @dev Returns the decimals places of the token.
 */
 function decimals() external view returns (uint8);
}


// File @openzeppelin/contracts/utils/Context.sol@v4.8.3

// 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/token/ERC20/ERC20.sol@v4.8.3

// OpenZeppelin Contracts (last updated v4.8.0) (token/ERC20/ERC20.sol)

pragma solidity ^0.8.0;



/**
 * @dev Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 * For a generic mechanism see {ERC20PresetMinterPauser}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.openzeppelin.com/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * We have followed general OpenZeppelin Contracts guidelines: functions revert
 * instead returning `false` on failure. This behavior is nonetheless
 * conventional and does not conflict with the expectations of ERC20
 * applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 */
contract ERC20 is Context, IERC20, IERC20Metadata {
 mapping(address => uint256) private _balances;

 mapping(address => mapping(address => uint256)) private _allowances;

 uint256 private _totalSupply;

 string private _name;
 string private _symbol;

 /**
 * @dev Sets the values for {name} and {symbol}.
 *
 * The default value of {decimals} is 18. To select a different value for
 * {decimals} you should overload it.
 *
 * All two of these values are immutable: they can only be set once during
 * construction.
 */
 constructor(string memory name_, string memory symbol_) {
 _name = name_;
 _symbol = symbol_;
 }

 /**
 * @dev Returns the name of the token.
 */
 function name() public view virtual override returns (string memory) {
 return _name;
 }

 /**
 * @dev Returns the symbol of the token, usually a shorter version of the
 * name.
 */
 function symbol() public view virtual override returns (string memory) {
 return _symbol;
 }

 /**
 * @dev Returns the number of decimals used to get its user representation.
 * For example, if `decimals` equals `2`, a balance of `505` tokens should
 * be displayed to a user as `5.05` (`505 / 10 ** 2`).
 *
 * Tokens usually opt for a value of 18, imitating the relationship between
 * Ether and Wei. This is the value {ERC20} uses, unless this function is
  * overridden;
 *
 * NOTE: This information is only used for _display_ purposes: it in
 * no way affects any of the arithmetic of the contract, including
 * {IERC20-balanceOf} and {IERC20-transfer}.
 */
 function decimals() public view virtual override returns (uint8) {
 return 18;
 }

 /**
 * @dev See {IERC20-totalSupply}.
 */
 function totalSupply() public view virtual override returns (uint256) {
 return _totalSupply;
 }

 /**
 * @dev See {IERC20-balanceOf}.
 */
 function balanceOf(address account) public view virtual override returns (uint256) {
 return _balances[account];
 }

 /**
 * @dev See {IERC20-transfer}.
 *
 * Requirements:
 *
 * - `to` cannot be the zero address.
 * - the caller must have a balance of at least `amount`.
 */
 function transfer(address to, uint256 amount) public virtual override returns (bool) {
 address owner = _msgSender();
 _transfer(owner, to, amount);
 return true;
 }

 /**
 * @dev See {IERC20-allowance}.
 */
 function allowance(address owner, address spender) public view virtual override returns (uint256) {
 return _allowances[owner][spender];
 }

 /**
 * @dev See {IERC20-approve}.
 *
 * NOTE: If `amount` is the maximum `uint256`, the allowance is not updated on
 * `transferFrom`. This is semantically equivalent to an infinite approval.
 *
 * Requirements:
 *
 * - `spender` cannot be the zero address.
 */
 function approve(address spender, uint256 amount) public virtual override returns (bool) {
 address owner = _msgSender();
 _approve(owner, spender, amount);
 return true;
 }

 /**
 * @dev See {IERC20-transferFrom}.
 *
 * Emits an {Approval} event indicating the updated allowance. This is not
 * required by the EIP. See the note at the beginning of {ERC20}.
 *
 * NOTE: Does not update the allowance if the current allowance
 * is the maximum `uint256`.
 *
 * Requirements:
 *
 * - `from` and `to` cannot be the zero address.
 * - `from` must have a balance of at least `amount`.
 * - the caller must have allowance for ``from``'s tokens of at least
 * `amount`.
 */
 function transferFrom(
 address from,
 address to,
 uint256 amount
 ) public virtual override returns (bool) {
 address spender = _msgSender();
 _spendAllowance(from, spender, amount);
 _transfer(from, to, amount);
 return true;
 }

 /**
 * @dev Atomically increases the allowance granted to `spender` by the caller.
 *
 * This is an alternative to {approve} that can be used as a mitigation for
 * problems described in {IERC20-approve}.
 *
 * Emits an {Approval} event indicating the updated allowance.
 *
 * Requirements:
 *
 * - `spender` cannot be the zero address.
 */
 function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
 address owner = _msgSender();
 _approve(owner, spender, allowance(owner, spender) + addedValue);
 return true;
 }

 /**
 * @dev Atomically decreases the allowance granted to `spender` by the caller.
 *
 * This is an alternative to {approve} that can be used as a mitigation for
 * problems described in {IERC20-approve}.
 *
 * Emits an {Approval} event indicating the updated allowance.
 *
 * Requirements:
 *
 * - `spender` cannot be the zero address.
 * - `spender` must have allowance for the caller of at least
 * `subtractedValue`.
 */
  function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
 address owner = _msgSender();
 uint256 currentAllowance = allowance(owner, spender);
 require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
 unchecked {
 _approve(owner, spender, currentAllowance - subtractedValue);
 }

 return true;
 }

 /**
 * @dev Moves `amount` of tokens from `from` to `to`.
 *
 * This internal function is equivalent to {transfer}, and can be used to
 * e.g. implement automatic token fees, slashing mechanisms, etc.
 *
 * Emits a {Transfer} event.
 *
 * Requirements:
 *
 * - `from` cannot be the zero address.
 * - `to` cannot be the zero address.
 * - `from` must have a balance of at least `amount`.
 */
 function _transfer(
 address from,
 address to,
 uint256 amount
 ) internal virtual {
 require(from != address(0), "ERC20: transfer from the zero address");
 require(to != address(0), "ERC20: transfer to the zero address");

 _beforeTokenTransfer(from, to, amount);

 uint256 fromBalance = _balances[from];
 require(fromBalance >= amount, "ERC20: transfer amount exceeds balance");
 unchecked {
 _balances[from] = fromBalance - amount;
 // Overflow not possible: the sum of all balances is capped by totalSupply, and the sum is preserved by
 // decrementing then incrementing.
 _balances[to] += amount;
 }

 emit Transfer(from, to, amount);

 _afterTokenTransfer(from, to, amount);
 }

 /** @dev Creates `amount` tokens and assigns them to `account`, increasing
 * the total supply.
 *
 * Emits a {Transfer} event with `from` set to the zero address.
 *
 * Requirements:
 *
 * - `account` cannot be the zero address.
 */
 function _mint(address account, uint256 amount) internal virtual {
 require(account != address(0), "ERC20: mint to the zero address");

 _beforeTokenTransfer(address(0), account, amount);

 _totalSupply += amount;
 unchecked {
 // Overflow not possible: balance + amount is at most totalSupply + amount, which is checked above.
 _balances[account] += amount;
 }
 emit Transfer(address(0), account, amount);

 _afterTokenTransfer(address(0), account, amount);
 }

 /**
 * @dev Destroys `amount` tokens from `account`, reducing the
 * total supply.
 *
 * Emits a {Transfer} event with `to` set to the zero address.
 *
 * Requirements:
 *
 * - `account` cannot be the zero address.
 * - `account` must have at least `amount` tokens.
 */
 function _burn(address account, uint256 amount) internal virtual {
 require(account != address(0), "ERC20: burn from the zero address");

 _beforeTokenTransfer(account, address(0), amount);

 uint256 accountBalance = _balances[account];
 require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
 unchecked {
 _balances[account] = accountBalance - amount;
 // Overflow not possible: amount <= accountBalance <= totalSupply.
 _totalSupply -= amount;
 }

 emit Transfer(account, address(0), amount);

 _afterTokenTransfer(account, address(0), amount);
 }

 /**
 * @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
 *
 * This internal function is equivalent to `approve`, and can be used to
 * e.g. set automatic allowances for certain subsystems, etc.
 *
 * Emits an {Approval} event.
 *
 * Requirements:
 *
 * - `owner` cannot be the zero address.
 * - `spender` cannot be the zero address.
 */
 function _approve(
 address owner,
 address spender,
 uint256 amount
 ) internal virtual {
 require(owner != address(0), "ERC20: approve from the zero address");
 require(spender != address(0), "ERC20: approve to the zero address");

 _allowances[owner][spender] = amount;
 emit Approval(owner, spender, amount);
 }

 /**
 * @dev Updates `owner` s allowance for `spender` based on spent `amount`.
 *
 * Does not update the allowance amount in case of infinite allowance.
 * Revert if not enough allowance is available.
 *
 * Might emit an {Approval} event.
 */
 function _spendAllowance(
 address owner,
 address spender,
 uint256 amount
 ) internal virtual {
 uint256 currentAllowance = allowance(owner, spender);
 if (currentAllowance != type(uint256).max) {
 require(currentAllowance >= amount, "ERC20: insufficient allowance");
 unchecked {
 _approve(owner, spender, currentAllowance - amount);
 }
 }
 }

 /**
 * @dev Hook that is called before any transfer of tokens. This includes
 * minting and burning.
 *
 * Calling conditions:
 *
 * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
 * will be transferred to `to`.
 * - when `from` is zero, `amount` tokens will be minted for `to`.
 * - when `to` is zero, `amount` of ``from``'s tokens 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 amount
 ) 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, `amount` of ``from``'s tokens
 * has been transferred to `to`.
 * - when `from` is zero, `amount` tokens have been minted for `to`.
 * - when `to` is zero, `amount` of ``from``'s tokens have been 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 _afterTokenTransfer(
 address from,
 address to,
 uint256 amount
 ) internal virtual {}
}


// File @openzeppelin/contracts/token/ERC20/extensions/draft-IERC20Permit.sol@v4.8.3

// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/draft-IERC20Permit.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
 * https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
 *
 * Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
 * presenting a message signed by the account. By not relying on {IERC20-approve}, the token holder account doesn't
 * need to send a transaction, and thus is not required to hold Ether at all.
 */
interface IERC20Permit {
 /**
 * @dev Sets `value` as the allowance of `spender` over ``owner``'s tokens,
 * given ``owner``'s signed approval.
 *
 * IMPORTANT: The same issues {IERC20-approve} has related to transaction
 * ordering also apply here.
 *
 * Emits an {Approval} event.
 *
 * Requirements:
 *
 * - `spender` cannot be the zero address.
 * - `deadline` must be a timestamp in the future.
 * - `v`, `r` and `s` must be a valid `secp256k1` signature from `owner`
 * over the EIP712-formatted function arguments.
 * - the signature must use ``owner``'s current nonce (see {nonces}).
 *
 * For more information on the signature format, see the
 * https://eips.ethereum.org/EIPS/eip-2612#specification[relevant EIP
 * section].
 */
 function permit(
 address owner,
 address spender,
 uint256 value,
 uint256 deadline,
 uint8 v,
 bytes32 r,
 bytes32 s
 ) external;

 /**
 * @dev Returns the current nonce for `owner`. This value must be
 * included whenever a signature is generated for {permit}.
 *
 * Every successful call to {permit} increases ``owner``'s nonce by one. This
 * prevents a signature from being used multiple times.
 */
 function nonces(address owner) external view returns (uint256);

 /**
 * @dev Returns the domain separator used in the encoding of the signature for {permit}, as defined by {EIP712}.
 */
 // solhint-disable-next-line func-name-mixedcase
 function DOMAIN_SEPARATOR() external view returns (bytes32);
}


// File @openzeppelin/contracts/utils/math/Math.sol@v4.8.3

// OpenZeppelin Contracts (last updated v4.8.0) (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 Hensel's 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 don't 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. If the number is not a perfect square, the value is rounded down.
 *
 * Inspired by Henry S. Warren, Jr.'s "Hacker's 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)`. This value can be written `msb(a)=2**k` with `k=log2(a)`.
 //
 // This can be rewritten `2**log2(a) <= a < 2**(log2(a) + 1)`
 // → `sqrt(2**k) <= sqrt(a) < sqrt(2**(k+1))`
 // → `2**(k/2) <= sqrt(a) < 2**((k+1)/2) <= 2**(k/2 + 1)`
 //
 // Consequently, `2**(log2(a) / 2)` is a good first approximation of `sqrt(a)` with at least 1 correct bit.
 uint256 result = 1 << (log2(a) >> 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. Newton's 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) {
 unchecked {
 uint256 result = sqrt(a);
 return result + (rounding == Rounding.Up && result * result < a ? 1 : 0);
 }
 }

 /**
 * @dev Return the log in base 2, rounded down, of a positive value.
 * Returns 0 if given 0.
 */
 function log2(uint256 value) internal pure returns (uint256) {
 uint256 result = 0;
 unchecked {
 if (value >> 128 > 0) {
 value >>= 128;
 result += 128;
 }
 if (value >> 64 > 0) {
 value >>= 64;
 result += 64;
 }
 if (value >> 32 > 0) {
 value >>= 32;
 result += 32;
 }
 if (value >> 16 > 0) {
 value >>= 16;
 result += 16;
 }
 if (value >> 8 > 0) {
 value >>= 8;
 result += 8;
 }
 if (value >> 4 > 0) {
 value >>= 4;
 result += 4;
 }
 if (value >> 2 > 0) {
 value >>= 2;
 result += 2;
 }
 if (value >> 1 > 0) {
 result += 1;
 }
 }
 return result;
 }

 /**
 * @dev Return the log in base 2, following the selected rounding direction, of a positive value.
 * Returns 0 if given 0.
 */
 function log2(uint256 value, Rounding rounding) internal pure returns (uint256) {
 unchecked {
 uint256 result = log2(value);
 return result + (rounding == Rounding.Up && 1 << result < value ? 1 : 0);
 }
 }

 /**
 * @dev Return the log in base 10, rounded down, of a positive value.
 * Returns 0 if given 0.
 */
 function log10(uint256 value) internal pure returns (uint256) {
 uint256 result = 0;
 unchecked {
 if (value >= 10**64) {
 value /= 10**64;
 result += 64;
 }
 if (value >= 10**32) {
 value /= 10**32;
 result += 32;
 }
 if (value >= 10**16) {
 value /= 10**16;
 result += 16;
 }
 if (value >= 10**8) {
 value /= 10**8;
 result += 8;
 }
 if (value >= 10**4) {
 value /= 10**4;
 result += 4;
 }
 if (value >= 10**2) {
 value /= 10**2;
 result += 2;
 }
 if (value >= 10**1) {
 result += 1;
 }
 }
 return result;
 }

 /**
 * @dev Return the log in base 10, following the selected rounding direction, of a positive value.
 * Returns 0 if given 0.
 */
 function log10(uint256 value, Rounding rounding) internal pure returns (uint256) {
 unchecked {
 uint256 result = log10(value);
 return result + (rounding == Rounding.Up && 10**result < value ? 1 : 0);
 }
 }

 /**
 * @dev Return the log in base 256, rounded down, of a positive value.
 * Returns 0 if given 0.
 *
 * Adding one to the result gives the number of pairs of hex symbols needed to represent `value` as a hex string.
 */
 function log256(uint256 value) internal pure returns (uint256) {
 uint256 result = 0;
 unchecked {
 if (value >> 128 > 0) {
 value >>= 128;
 result += 16;
 }
 if (value >> 64 > 0) {
 value >>= 64;
 result += 8;
 }
 if (value >> 32 > 0) {
 value >>= 32;
 result += 4;
 }
 if (value >> 16 > 0) {
 value >>= 16;
 result += 2;
 }
 if (value >> 8 > 0) {
 result += 1;
 }
 }
 return result;
 }

 /**
 * @dev Return the log in base 10, following the selected rounding direction, of a positive value.
 * Returns 0 if given 0.
 */
 function log256(uint256 value, Rounding rounding) internal pure returns (uint256) {
 unchecked {
 uint256 result = log256(value);
 return result + (rounding == Rounding.Up && 1 << (result * 8) < value ? 1 : 0);
 }
 }
}


// File @openzeppelin/contracts/utils/Strings.sol@v4.8.3

// OpenZeppelin Contracts (last updated v4.8.0) (utils/Strings.sol)

pragma solidity ^0.8.0;

/**
 * @dev String operations.
 */
library Strings {
 bytes16 private constant _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) {
 unchecked {
 uint256 length = Math.log10(value) + 1;
 string memory buffer = new string(length);
 uint256 ptr;
 /// @solidity memory-safe-assembly
 assembly {
 ptr := add(buffer, add(32, length))
 }
 while (true) {
 ptr--;
 /// @solidity memory-safe-assembly
 assembly {
 mstore8(ptr, byte(mod(value, 10), _SYMBOLS))
 }
 value /= 10;
 if (value == 0) break;
 }
 return buffer;
 }
 }

 /**
 * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
 */
 function toHexString(uint256 value) internal pure returns (string memory) {
 unchecked {
 return toHexString(value, Math.log256(value) + 1);
 }
 }

 /**
 * @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] = _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/cryptography/ECDSA.sol@v4.8.3

// OpenZeppelin Contracts (last updated v4.8.0) (utils/cryptography/ECDSA.sol)

pragma solidity ^0.8.0;

/**
 * @dev Elliptic Curve Digital Signature Algorithm (ECDSA) operations.
 *
 * These functions can be used to verify that a message was signed by the holder
 * of the private keys of a given address.
 */
library ECDSA {
 enum RecoverError {
 NoError,
 InvalidSignature,
 InvalidSignatureLength,
 InvalidSignatureS,
 InvalidSignatureV // Deprecated in v4.8
 }

 function _throwError(RecoverError error) private pure {
 if (error == RecoverError.NoError) {
 return; // no error: do nothing
 } else if (error == RecoverError.InvalidSignature) {
 revert("ECDSA: invalid signature");
 } else if (error == RecoverError.InvalidSignatureLength) {
 revert("ECDSA: invalid signature length");
 } else if (error == RecoverError.InvalidSignatureS) {
 revert("ECDSA: invalid signature 's' value");
 }
 }

 /**
 * @dev Returns the address that signed a hashed message (`hash`) with
 * `signature` or error string. This address can then be used for verification purposes.
 *
 * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
 * this function rejects them by requiring the `s` value to be in the lower
 * half order, and the `v` value to be either 27 or 28.
 *
 * IMPORTANT: `hash` _must_ be the result of a hash operation for the
 * verification to be secure: it is possible to craft signatures that
 * recover to arbitrary addresses for non-hashed data. A safe way to ensure
 * this is by receiving a hash of the original message (which may otherwise
 * be too long), and then calling {toEthSignedMessageHash} on it.
 *
 * Documentation for signature generation:
 * - with https://web3js.readthedocs.io/en/v1.3.4/web3-eth-accounts.html#sign[Web3.js]
 * - with https://docs.ethers.io/v5/api/signer/#Signer-signMessage[ethers]
 *
 * _Available since v4.3._
 */
 function tryRecover(bytes32 hash, bytes memory signature) internal pure returns (address, RecoverError) {
 if (signature.length == 65) {
 bytes32 r;
 bytes32 s;
 uint8 v;
 // ecrecover takes the signature parameters, and the only way to get them
 // currently is to use assembly.
 /// @solidity memory-safe-assembly
 assembly {
 r := mload(add(signature, 0x20))
 s := mload(add(signature, 0x40))
 v := byte(0, mload(add(signature, 0x60)))
 }
 return tryRecover(hash, v, r, s);
 } else {
 return (address(0), RecoverError.InvalidSignatureLength);
 }
 }

 /**
 * @dev Returns the address that signed a hashed message (`hash`) with
 * `signature`. This address can then be used for verification purposes.
 *
 * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
 * this function rejects them by requiring the `s` value to be in the lower
 * half order, and the `v` value to be either 27 or 28.
 *
 * IMPORTANT: `hash` _must_ be the result of a hash operation for the
 * verification to be secure: it is possible to craft signatures that
 * recover to arbitrary addresses for non-hashed data. A safe way to ensure
 * this is by receiving a hash of the original message (which may otherwise
 * be too long), and then calling {toEthSignedMessageHash} on it.
 */
 function recover(bytes32 hash, bytes memory signature) internal pure returns (address) {
 (address recovered, RecoverError error) = tryRecover(hash, signature);
 _throwError(error);
 return recovered;
 }

 /**
 * @dev Overload of {ECDSA-tryRecover} that receives the `r` and `vs` short-signature fields separately.
 *
 * See https://eips.ethereum.org/EIPS/eip-2098[EIP-2098 short signatures]
 *
 * _Available since v4.3._
 */
 function tryRecover(
 bytes32 hash,
 bytes32 r,
 bytes32 vs
 ) internal pure returns (address, RecoverError) {
 bytes32 s = vs & bytes32(0x7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff);
 uint8 v = uint8((uint256(vs) >> 255) + 27);
 return tryRecover(hash, v, r, s);
 }

 /**
 * @dev Overload of {ECDSA-recover} that receives the `r and `vs` short-signature fields separately.
 *
 * _Available since v4.2._
 */
 function recover(
 bytes32 hash,
 bytes32 r,
 bytes32 vs
 ) internal pure returns (address) {
 (address recovered, RecoverError error) = tryRecover(hash, r, vs);
 _throwError(error);
 return recovered;
 }

 /**
 * @dev Overload of {ECDSA-tryRecover} that receives the `v`,
 * `r` and `s` signature fields separately.
 *
 * _Available since v4.3._
 */
 function tryRecover(
 bytes32 hash,
 uint8 v,
 bytes32 r,
 bytes32 s
 ) internal pure returns (address, RecoverError) {
 // EIP-2 still allows signature malleability for ecrecover(). Remove this possibility and make the signature
 // unique. Appendix F in the Ethereum Yellow paper (https://ethereum.github.io/yellowpaper/paper.pdf), defines
 // the valid range for s in (301): 0 < s < secp256k1n ÷ 2 + 1, and for v in (302): v ∈ {27, 28}. Most
 // signatures from current libraries generate a unique signature with an s-value in the lower half order.
 //
 // If your library generates malleable signatures, such as s-values in the upper range, calculate a new s-value
 // with 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141 - s1 and flip v from 27 to 28 or
 // vice versa. If your library also generates signatures with 0/1 for v instead 27/28, add 27 to v to accept
 // these malleable signatures as well.
 if (uint256(s) > 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0) {
 return (address(0), RecoverError.InvalidSignatureS);
 }

 // If the signature is valid (and not malleable), return the signer address
 address signer = ecrecover(hash, v, r, s);
 if (signer == address(0)) {
 return (address(0), RecoverError.InvalidSignature);
 }

 return (signer, RecoverError.NoError);
 }

 /**
 * @dev Overload of {ECDSA-recover} that receives the `v`,
 * `r` and `s` signature fields separately.
 */
 function recover(
 bytes32 hash,
 uint8 v,
 bytes32 r,
 bytes32 s
 ) internal pure returns (address) {
 (address recovered, RecoverError error) = tryRecover(hash, v, r, s);
 _throwError(error);
 return recovered;
 }

 /**
 * @dev Returns an Ethereum Signed Message, created from a `hash`. This
 * produces hash corresponding to the one signed with the
 * https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]
 * JSON-RPC method as part of EIP-191.
 *
 * See {recover}.
 */
 function toEthSignedMessageHash(bytes32 hash) internal pure returns (bytes32) {
 // 32 is the length in bytes of hash,
 // enforced by the type signature above
 return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", hash));
 }

 /**
 * @dev Returns an Ethereum Signed Message, created from `s`. This
 * produces hash corresponding to the one signed with the
 * https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]
 * JSON-RPC method as part of EIP-191.
 *
 * See {recover}.
 */
 function toEthSignedMessageHash(bytes memory s) internal pure returns (bytes32) {
 return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n", Strings.toString(s.length), s));
 }

 /**
 * @dev Returns an Ethereum Signed Typed Data, created from a
 * `domainSeparator` and a `structHash`. This produces hash corresponding
 * to the one signed with the
 * https://eips.ethereum.org/EIPS/eip-712[`eth_signTypedData`]
 * JSON-RPC method as part of EIP-712.
 *
 * See {recover}.
 */
 function toTypedDataHash(bytes32 domainSeparator, bytes32 structHash) internal pure returns (bytes32) {
 return keccak256(abi.encodePacked("\x19\x01", domainSeparator, structHash));
 }
}


// File @openzeppelin/contracts/utils/cryptography/EIP712.sol@v4.8.3

// OpenZeppelin Contracts (last updated v4.8.0) (utils/cryptography/EIP712.sol)

pragma solidity ^0.8.0;

/**
 * @dev https://eips.ethereum.org/EIPS/eip-712[EIP 712] is a standard for hashing and signing of typed structured data.
 *
 * The encoding specified in the EIP is very generic, and such a generic implementation in Solidity is not feasible,
 * thus this contract does not implement the encoding itself. Protocols need to implement the type-specific encoding
 * they need in their contracts using a combination of `abi.encode` and `keccak256`.
 *
 * This contract implements the EIP 712 domain separator ({_domainSeparatorV4}) that is used as part of the encoding
 * scheme, and the final step of the encoding to obtain the message digest that is then signed via ECDSA
 * ({_hashTypedDataV4}).
 *
 * The implementation of the domain separator was designed to be as efficient as possible while still properly updating
 * the chain id to protect against replay attacks on an eventual fork of the chain.
 *
 * NOTE: This contract implements the version of the encoding known as "v4", as implemented by the JSON RPC method
 * https://docs.metamask.io/guide/signing-data.html[`eth_signTypedDataV4` in MetaMask].
 *
 * _Available since v3.4._
 */
abstract contract EIP712 {
 /* solhint-disable var-name-mixedcase */
 // Cache the domain separator as an immutable value, but also store the chain id that it corresponds to, in order to
 // invalidate the cached domain separator if the chain id changes.
 bytes32 private immutable _CACHED_DOMAIN_SEPARATOR;
 uint256 private immutable _CACHED_CHAIN_ID;
 address private immutable _CACHED_THIS;

 bytes32 private immutable _HASHED_NAME;
 bytes32 private immutable _HASHED_VERSION;
 bytes32 private immutable _TYPE_HASH;

 /* solhint-enable var-name-mixedcase */

 /**
 * @dev Initializes the domain separator and parameter caches.
 *
 * The meaning of `name` and `version` is specified in
 * https://eips.ethereum.org/EIPS/eip-712#definition-of-domainseparator[EIP 712]:
 *
 * - `name`: the user readable name of the signing domain, i.e. the name of the DApp or the protocol.
 * - `version`: the current major version of the signing domain.
 *
 * NOTE: These parameters cannot be changed except through a xref:learn::upgrading-smart-contracts.adoc[smart
 * contract upgrade].
 */
 constructor(string memory name, string memory version) {
 bytes32 hashedName = keccak256(bytes(name));
 bytes32 hashedVersion = keccak256(bytes(version));
 bytes32 typeHash = keccak256(
 "EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"
 );
 _HASHED_NAME = hashedName;
 _HASHED_VERSION = hashedVersion;
 _CACHED_CHAIN_ID = block.chainid;
 _CACHED_DOMAIN_SEPARATOR = _buildDomainSeparator(typeHash, hashedName, hashedVersion);
 _CACHED_THIS = address(this);
 _TYPE_HASH = typeHash;
 }

 /**
 * @dev Returns the domain separator for the current chain.
 */
 function _domainSeparatorV4() internal view returns (bytes32) {
 if (address(this) == _CACHED_THIS && block.chainid == _CACHED_CHAIN_ID) {
 return _CACHED_DOMAIN_SEPARATOR;
 } else {
 return _buildDomainSeparator(_TYPE_HASH, _HASHED_NAME, _HASHED_VERSION);
 }
 }

 function _buildDomainSeparator(
 bytes32 typeHash,
 bytes32 nameHash,
 bytes32 versionHash
 ) private view returns (bytes32) {
 return keccak256(abi.encode(typeHash, nameHash, versionHash, block.chainid, address(this)));
 }

 /**
 * @dev Given an already https://eips.ethereum.org/EIPS/eip-712#definition-of-hashstruct[hashed struct], this
 * function returns the hash of the fully encoded EIP712 message for this domain.
 *
 * This hash can be used together with {ECDSA-recover} to obtain the signer of a message. For example:
 *
 * ```solidity
 * bytes32 digest = _hashTypedDataV4(keccak256(abi.encode(
 * keccak256("Mail(address to,string contents)"),
 * mailTo,
 * keccak256(bytes(mailContents))
 * )));
 * address signer = ECDSA.recover(digest, signature);
 * ```
 */
 function _hashTypedDataV4(bytes32 structHash) internal view virtual returns (bytes32) {
 return ECDSA.toTypedDataHash(_domainSeparatorV4(), structHash);
 }
}


// File @openzeppelin/contracts/utils/Counters.sol@v4.8.3

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

pragma solidity ^0.8.0;

/**
 * @title Counters
 * @author Matt Condon (@shrugs)
 * @dev Provides counters that can only be incremented, decremented or reset. This can be used e.g. to track the number
 * of elements in a mapping, issuing ERC721 ids, or counting request ids.
 *
 * Include with `using Counters for Counters.Counter;`
 */
library Counters {
 struct Counter {
 // This variable should never be directly accessed by users of the library: interactions must be restricted to
 // the library's function. As of Solidity v0.5.2, this cannot be enforced, though there is a proposal to add
 // this feature: see https://github.com/ethereum/solidity/issues/4637
 uint256 _value; // default: 0
 }

 function current(Counter storage counter) internal view returns (uint256) {
 return counter._value;
 }

 function increment(Counter storage counter) internal {
 unchecked {
 counter._value += 1;
 }
 }
 
 function decrement(Counter storage counter) internal {
 uint256 value = counter._value;
 require(value > 0, "Counter: decrement overflow");
 unchecked {
 counter._value = value - 1;
 }
 }

 function reset(Counter storage counter) internal {
 counter._value = 0;
 }
}


// File @openzeppelin/contracts/token/ERC20/extensions/draft-ERC20Permit.sol@v4.8.3

// OpenZeppelin Contracts (last updated v4.8.0) (token/ERC20/extensions/draft-ERC20Permit.sol)

pragma solidity ^0.8.0;





/**
 * @dev Implementation of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
 * https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
 *
 * Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
 * presenting a message signed by the account. By not relying on `{IERC20-approve}`, the token holder account doesn't
 * need to send a transaction, and thus is not required to hold Ether at all.
 *
 * _Available since v3.4._
 */
abstract contract ERC20Permit is ERC20, IERC20Permit, EIP712 {
 using Counters for Counters.Counter;

 mapping(address => Counters.Counter) private _nonces;

 // solhint-disable-next-line var-name-mixedcase
 bytes32 private constant _PERMIT_TYPEHASH =
 keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)");
 /**
 * @dev In previous versions `_PERMIT_TYPEHASH` was declared as `immutable`.
 * However, to ensure consistency with the upgradeable transpiler, we will continue
 * to reserve a slot.
 * @custom:oz-renamed-from _PERMIT_TYPEHASH
 */
 // solhint-disable-next-line var-name-mixedcase
 bytes32 private _PERMIT_TYPEHASH_DEPRECATED_SLOT;

 /**
 * @dev Initializes the {EIP712} domain separator using the `name` parameter, and setting `version` to `"1"`.
 *
 * It's a good idea to use the same `name` that is defined as the ERC20 token name.
 */
 constructor(string memory name) EIP712(name, "1") {}

 /**
 * @dev See {IERC20Permit-permit}.
 */
 function permit(
 address owner,
 address spender,
 uint256 value,
 uint256 deadline,
 uint8 v,
 bytes32 r,
 bytes32 s
 ) public virtual override {
 require(block.timestamp <= deadline, "ERC20Permit: expired deadline");

 bytes32 structHash = keccak256(abi.encode(_PERMIT_TYPEHASH, owner, spender, value, _useNonce(owner), deadline));

 bytes32 hash = _hashTypedDataV4(structHash);

 address signer = ECDSA.recover(hash, v, r, s);
 require(signer == owner, "ERC20Permit: invalid signature");

 _approve(owner, spender, value);
 }

 /**
 * @dev See {IERC20Permit-nonces}.
 */
 function nonces(address owner) public view virtual override returns (uint256) {
 return _nonces[owner].current();
 }

 /**
 * @dev See {IERC20Permit-DOMAIN_SEPARATOR}.
 */
 // solhint-disable-next-line func-name-mixedcase
 function DOMAIN_SEPARATOR() external view override returns (bytes32) {
 return _domainSeparatorV4();
 }

 /**
 * @dev "Consume a nonce": return the current value and increment.
 *
 * _Available since v4.1._
 */
 function _useNonce(address owner) internal virtual returns (uint256 current) {
 Counters.Counter storage nonce = _nonces[owner];
 current = nonce.current();
 nonce.increment();
 }
}


// File @openzeppelin/contracts/access/Ownable.sol@v4.8.3

// 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 contracts/Presale.sol


 //******* ** ** ******* ******* 	 \_A__ A A AA ___/
///**////** //** ** **/////** /**////** 	 \____ ^^^^^^^^ ___/
///** /** //**** ** //**/** /** \| |/ /\_/\ 
///** /** //** /** /**/******* ___ /\_/\ | | ((@v@)) __/ 
///** /** /** /** /**/**///** (o,o) ((@v@)) | | ():::() / 
///** ** /** //** ** /** //** < . > ():::() | |------VV-VV------ 
///******* /** //******* /** //** ------"-"----VV-VV---| |----------------- 
///////// // /////// // // ---------------------| | \__ 
 
pragma solidity ^0.8.9;
contract DRUGON is ERC20, Ownable, ERC20Permit {
 constructor() ERC20("DRUGON", "DRUGON") ERC20Permit("DRUGON"){}

 /// turn on/off contributions, determines whether presale is active
 bool public allowContributions = false;

 /// turn on/off refunds
 bool public allowRefund = false;

 /// mint LP once
 bool public lpMinted = false;

 /// a minimum contribution per tx to participate in the presale
 uint256 public constant MIN_CONTRIBUTION = .025 ether;

 /// limit the maximum contribution per tx for each wallet
 uint256 public constant MAX_CONTRIBUTION = .25 ether;

 /// the maximum amount of eth that this contract will accept for presale
 uint256 public constant HARD_CAP = 25 ether;

 /// total number of tokens available
 uint256 public constant MAX_SUPPLY = 400_000_000_000 * 10 ** 18;

 /// 50% of tokens reserved for presale
 uint256 public constant PRESALE_SUPPLY = 140_000_000_000 * 10 ** 18;

 /// 40% of tokens reserved for LP
 uint256 public constant LP_SUPPLY = 220_000_000_000 * 10 ** 18;

 /// used to track the total contributions for the presale
 uint256 public TOTAL_CONTRIBUTED;

 /// used to track the total number of contributoors
 uint256 public NUMBER_OF_CONTRIBUTOORS;

 uint256 public AIRDROP_INDEX = 1;

 /// a struct used to keep track of each contributoors address and contribution amount
 struct Contribution {
    address addr;
    uint256 amount;
 }

 /// mapping of contributions
 mapping (uint256 => Contribution) public contribution;

 /// index of an address to it's contribition information
 mapping (address => uint256) public contributoor;

 /// collect presale contributions
 function sendToPresale() public payable {

    /// initialize a contribution index so we can keep track of this address' contributions
    uint256 contributionIndex;

    /// check to see if contributions are allowed
    require (allowContributions, "Contributions not allowed");

    /// check to see that at least the min is being sent in
    require(msg.value >= MIN_CONTRIBUTION, "Contribution too low");

    /// enforce per-wallet contribution limit
    require (msg.value <= MAX_CONTRIBUTION, "Contribution exceeds per wallet limit");

    /// enforce hard cap
    require (msg.value + TOTAL_CONTRIBUTED <= HARD_CAP, "Contribution exceeds hard cap"); 

    if (contributoor[msg.sender] != 0){
    /// no need to increase the number of contributors since this person already added
    contributionIndex = contributoor[msg.sender];
    } else {
    /// keep track of each new contributor with a unique index
    contributionIndex = NUMBER_OF_CONTRIBUTOORS + 1;
    NUMBER_OF_CONTRIBUTOORS++;
    contributoor[msg.sender] = contributionIndex;
    contribution[contributionIndex].addr = msg.sender;
    }

    /// add the contribution to the amount contributed
    TOTAL_CONTRIBUTED = TOTAL_CONTRIBUTED + msg.value;

    /// keep track of the address' contributions so far
    contribution[contributionIndex].amount += msg.value;
 }

 function airdropPresale(uint256 airdropamount) external onlyOwner {

    require (!allowContributions, "Presale is still on");

    /// determine the price per token
    uint256 pricePerToken = (HARD_CAP * 20 ** 18) / PRESALE_SUPPLY;

    //check to make sure you are not going over the number of contributoors
    uint256 minttoIndex = AIRDROP_INDEX + airdropamount;
    require(minttoIndex - 1 <= NUMBER_OF_CONTRIBUTOORS, "out of airdrop range");

    /// loop over each contribution and distribute tokens
    for (uint256 i = AIRDROP_INDEX; i < minttoIndex; i++) {

        /// convert contribution to 18 decimals
        uint256 contributionAmount = contribution[i].amount * 20 ** 18;

        /// calculate the percentage of the pool based on the address' contribution
        uint256 numberOfTokensToMint = contributionAmount/pricePerToken;

        /// mint the tokens to the address
        _mint(contribution[i].addr, numberOfTokensToMint);
    }

    // update starting index for next airdrop
    AIRDROP_INDEX = minttoIndex;
 }

 /// dev mint the remainder of the pool to round out the supply
 function devMint(address _address) external onlyOwner {

    /// calculate the remaining supply
    uint256 numberToMint = MAX_SUPPLY - totalSupply();

    //make sure contributions are set to false
    require (!allowContributions, "presale is still on");

    /// mint the remaining supply to the dev's wallet
    _mint(_address, numberToMint);
 }

 /// set whether or not the contract allows contributions
 function setAllowContributions(bool _value) external onlyOwner {
    allowContributions = _value;
 }

 /// set whether or not we want to scrub the project
 function setAllowRefund(bool _value) external onlyOwner {
    allowRefund = _value;
 }

 /// take your eth out
 function getRefund() public {
    require (allowRefund, "refund is not allowed");
    require (!allowContributions, "presale is still on");
    require(contributoor[msg.sender] != 0, "user did not contribute");

    uint256 contributionIndex = contributoor[msg.sender];
    uint256 amountToRefund = contribution[contributionIndex].amount;

    require(amountToRefund > 0, "nothing to refund");
    contribution[contributionIndex].amount = 0;

    address payable refundAddress = payable(contribution[contributionIndex].addr);
    refundAddress.transfer(amountToRefund);
 }

 /// mint the LP amount
    function mintLPAmount() external onlyOwner {
        require(!lpMinted, "LP Minted");
        lpMinted = true;
        _mint(msg.sender, LP_SUPPLY);
    }

 /// allows the owner to withdraw the funds in this contract
    function withdrawBalance(address payable _address) external onlyOwner {
        (bool success, ) = _address.call{value: address(this).balance}("");
        require(success, "Withdraw failed");
    }
}