// SPDX-License-Identifier: MIT
pragma solidity =0.6.11;
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/cryptography/MerkleProof.sol";
import "./interfaces/IMerkleDistributor.sol";
contract MerkleDistributor is IMerkleDistributor {
    address public immutable override token;
    bytes32 public override merkleRoot;
    address public owner;
    address public treasury;
    uint256 public claimRestTimeFrom;
    // This is a packed array of booleans.
    mapping(uint256 => uint256) private claimedBitMap;
    constructor(address token_, bytes32 merkleRoot_, address treasury_) public {
        token = token_;
        merkleRoot = merkleRoot_;
        owner = msg.sender;
        treasury = treasury_;
        claimRestTimeFrom = block.timestamp + 3 weeks;
    }
    function setOwner (address newOwner) public {
        require (owner == msg.sender, "only owner can set root");
        owner = newOwner;
    }
    function setroot (bytes32 newroot) public {
        require (owner == msg.sender, "only owner can set root");
        merkleRoot = newroot;
    }
    function contractTokenBalance() public view returns (uint) {
        return IERC20(token).balanceOf(address(this));
    }
    function claimRestOfTokensToTreasury() public returns (bool) {
        require(msg.sender == owner, "Only owner");
        require(block.timestamp >= claimRestTimeFrom, "Not yet claimable");
        require(IERC20(token).balanceOf(address(this)) >= 0, "No balance");
        require(IERC20(token).transfer(treasury, IERC20(token).balanceOf(address(this))));
        return true;
    }
    function isClaimed(uint256 index) public view override returns (bool) {
        uint256 claimedWordIndex = index / 256;
        uint256 claimedBitIndex = index % 256;
        uint256 claimedWord = claimedBitMap[claimedWordIndex];
        uint256 mask = (1 << claimedBitIndex);
        return claimedWord & mask == mask;
    }
    function _setClaimed(uint256 index) private {
        uint256 claimedWordIndex = index / 256;
        uint256 claimedBitIndex = index % 256;
        claimedBitMap[claimedWordIndex] = claimedBitMap[claimedWordIndex] | (1 << claimedBitIndex);
    }
    function claim(uint256 index, address account, uint256 amount, bytes32[] calldata merkleProof) external override {
        require(!isClaimed(index), 'MerkleDistributor: Drop already claimed.');
        // Verify the merkle proof.
        bytes32 node = keccak256(abi.encodePacked(index, account, amount));
        require(MerkleProof.verify(merkleProof, merkleRoot, node), 'MerkleDistributor: Invalid proof.');
        // Mark it claimed and send the token.
        _setClaimed(index);
        require(IERC20(token).transfer(account, amount), 'MerkleDistributor: Transfer failed.');
        emit Claimed(index, account, amount);
    }
}// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <0.8.0;
/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);
    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);
    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);
    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);
    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);
    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);
    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);
    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <0.8.0;
/**
 * @dev These functions deal with verification of Merkle trees (hash trees),
 */
library MerkleProof {
    /**
     * @dev Returns true if a `leaf` can be proved to be a part of a Merkle tree
     * defined by `root`. For this, a `proof` must be provided, containing
     * sibling hashes on the branch from the leaf to the root of the tree. Each
     * pair of leaves and each pair of pre-images are assumed to be sorted.
     */
    function verify(bytes32[] memory proof, bytes32 root, bytes32 leaf) internal pure returns (bool) {
        bytes32 computedHash = leaf;
        for (uint256 i = 0; i < proof.length; i++) {
            bytes32 proofElement = proof[i];
            if (computedHash <= proofElement) {
                // Hash(current computed hash + current element of the proof)
                computedHash = keccak256(abi.encodePacked(computedHash, proofElement));
            } else {
                // Hash(current element of the proof + current computed hash)
                computedHash = keccak256(abi.encodePacked(proofElement, computedHash));
            }
        }
        // Check if the computed hash (root) is equal to the provided root
        return computedHash == root;
    }
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.5.0;
// Allows anyone to claim a token if they exist in a merkle root.
interface IMerkleDistributor {
    // Returns the address of the token distributed by this contract.
    function token() external view returns (address);
    // Returns the merkle root of the merkle tree containing account balances available to claim.
    function merkleRoot() external view returns (bytes32);
    // Returns true if the index has been marked claimed.
    function isClaimed(uint256 index) external view returns (bool);
    // Claim the given amount of the token to the given address. Reverts if the inputs are invalid.
    function claim(uint256 index, address account, uint256 amount, bytes32[] calldata merkleProof) external;
    // This event is triggered whenever a call to #claim succeeds.
    event Claimed(uint256 index, address account, uint256 amount);
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.7.6;
pragma experimental ABIEncoderV2;
import "@openzeppelin/contracts/math/SafeMath.sol";
/// @author Alchemy Team
/// @title Alchemy
/// @notice The Alchemy Governance Token
contract ALCH {
    /// @notice EIP-20 token name for this token
    string public constant name = "Alchemy";
    /// @notice EIP-20 token symbol for this token
    string public constant symbol = "ALCH";
    /// @notice EIP-20 token decimals for this token
    uint8 public constant decimals = 18;
    /// @notice Address which may mint new tokens
    address public minter;
    /// @notice The timestamp after which minting may occur
    uint256 public mintingAllowedAfter;
    /// @notice Cap on the percentage of totalSupply that can be minted at each mint
    uint8 public constant mintCap = 10;
    /// @notice Minimum time between mints
    uint32 public constant minimumTimeBetweenMints = 90 days;
    /// @notice Total number of tokens in circulation
    uint256 public totalSupply = 10_000_000e18;
    mapping(address => mapping(address => uint96)) internal allowances;
    mapping(address => uint96) internal balances;
    mapping(address => address) public delegates;
    struct Checkpoint {
        uint32 fromBlock;
        uint96 votes;
    }
    mapping(address => mapping(uint32 => Checkpoint)) public checkpoints;
    mapping(address => uint32) public numCheckpoints;
    bytes32 public constant DOMAIN_TYPEHASH = keccak256(
        "EIP712Domain(string name,uint256 chainId,address verifyingContract)"
    );
    bytes32 public constant DELEGATION_TYPEHASH = keccak256(
        "Delegation(address delegatee,uint256 nonce,uint256 expiry)"
    );
    bytes32 public constant PERMIT_TYPEHASH = keccak256(
        "Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)"
    );
    mapping(address => uint256) public nonces;
    /// @notice An event thats emitted when the minter address is changed
    event MinterChanged(address minter, address newMinter);
    event DelegateChanged(
        address indexed delegator,
        address indexed fromDelegate,
        address indexed toDelegate
    );
    event DelegateVotesChanged(
        address indexed delegate,
        uint256 previousBalance,
        uint256 newBalance
    );
    event Transfer(address indexed from, address indexed to, uint256 amount);
    event Approval(
        address indexed owner,
        address indexed spender,
        uint256 amount
    );
    constructor(address account, address minter_, uint256 mintingAllowedAfter_) {
        require(
            mintingAllowedAfter_ >= block.timestamp,
            "Alch::constructor: minting can only begin after deployment"
        );
        balances[account] = uint96(totalSupply);
        emit Transfer(address(0), account, totalSupply);
        minter = minter_;
        emit MinterChanged(address(0), minter);
        mintingAllowedAfter = mintingAllowedAfter_;
    }
    /**
     * @notice Change the minter address
     * @param minter_ The address of the new minter
     */
    function setMinter(address minter_) external {
        require(msg.sender == minter, "Alch::setMinter: only the minter can change the minter address");
        emit MinterChanged(minter, minter_);
        minter = minter_;
    }
    /**
     * @notice Mint new tokens
     * @param dst The address of the destination account
     * @param rawAmount The number of tokens to be minted
     */
    function mint(address dst, uint rawAmount) external {
        require(msg.sender == minter, "Alch::mint: only the minter can mint");
        require(block.timestamp >= mintingAllowedAfter, "Alch::mint: minting not allowed yet");
        require(dst != address(0), "Alch::mint: cannot transfer to the zero address");
        // record the mint
        mintingAllowedAfter = SafeMath.add(block.timestamp, minimumTimeBetweenMints);
        // mint the amount
        uint96 amount = safe96(rawAmount, "Alch::mint: amount exceeds 96 bits");
        require(amount <= SafeMath.div(SafeMath.mul(totalSupply, mintCap), 100), "Alch::mint: exceeded mint cap");
        totalSupply = safe96(SafeMath.add(totalSupply, amount), "Alch::mint: totalSupply exceeds 96 bits");
        // transfer the amount to the recipient
        balances[dst] = add96(balances[dst], amount, "Alch::mint: transfer amount overflows");
        emit Transfer(address(0), dst, amount);
        // move delegates
        _moveDelegates(address(0), delegates[dst], amount);
    }
    function allowance(address account, address spender)
    external
    view
    returns (uint256)
    {
        return allowances[account][spender];
    }
    function approve(address spender, uint256 rawAmount) external returns (bool) {
        uint96 amount;
        if (rawAmount == uint256(-1)) {
            amount = uint96(-1);
        } else {
            amount = safe96(rawAmount, "Alch::approve: amount exceeds 96 bits");
        }
        allowances[msg.sender][spender] = amount;
        emit Approval(msg.sender, spender, amount);
        return true;
    }
    function permit(
        address owner,
        address spender,
        uint256 rawAmount,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external {
        uint96 amount;
        if (rawAmount == uint256(-1)) {
            amount = uint96(-1);
        } else {
            amount = safe96(rawAmount, "Alch::permit: amount exceeds 96 bits");
        }
        bytes32 domainSeparator = keccak256(
            abi.encode(
                DOMAIN_TYPEHASH,
                keccak256(bytes(name)),
                getChainId(),
                address(this)
            )
        );
        bytes32 structHash = keccak256(
            abi.encode(
                PERMIT_TYPEHASH,
                owner,
                spender,
                rawAmount,
                nonces[owner]++,
                deadline
            )
        );
        bytes32 digest = keccak256(
            abi.encodePacked("\\x19\\x01", domainSeparator, structHash)
        );
        address signatory = ecrecover(digest, v, r, s);
        require(signatory != address(0), "Alch::permit: invalid signature");
        require(signatory == owner, "Alch::permit: unauthorized");
        require(block.timestamp <= deadline, "Alch::permit: signature expired");
        allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }
    function balanceOf(address account) external view returns (uint256) {
        return balances[account];
    }
    function nonceOf(address account) external view returns (uint256) {
        return nonces[account];
    }
    function transfer(address dst, uint256 rawAmount) external returns (bool) {
        uint96 amount = safe96(rawAmount, "Alch::transfer: amount exceeds 96 bits");
        _transferTokens(msg.sender, dst, amount);
        return true;
    }
    function transferFrom(
        address src,
        address dst,
        uint256 rawAmount
    ) external returns (bool) {
        address spender = msg.sender;
        uint96 spenderAllowance = allowances[src][spender];
        uint96 amount = safe96(rawAmount, "Alch::approve: amount exceeds 96 bits");
        if (spender != src && spenderAllowance != uint96(-1)) {
            uint96 newAllowance = sub96(
                spenderAllowance,
                amount,
                "Alch::transferFrom: transfer amount exceeds spender allowance"
            );
            allowances[src][spender] = newAllowance;
            emit Approval(src, spender, newAllowance);
        }
        _transferTokens(src, dst, amount);
        return true;
    }
    function delegate(address delegatee) public {
        return _delegate(msg.sender, delegatee);
    }
    function delegateBySig(
        address delegatee,
        uint256 nonce,
        uint256 expiry,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) public {
        bytes32 domainSeparator = keccak256(
            abi.encode(
                DOMAIN_TYPEHASH,
                keccak256(bytes(name)),
                getChainId(),
                address(this)
            )
        );
        bytes32 structHash = keccak256(
            abi.encode(DELEGATION_TYPEHASH, delegatee, nonce, expiry)
        );
        bytes32 digest = keccak256(
            abi.encodePacked("\\x19\\x01", domainSeparator, structHash)
        );
        address signatory = ecrecover(digest, v, r, s);
        require(signatory != address(0), "Alch::delegateBySig: invalid signature");
        require(nonce == nonces[signatory]++, "Alch::delegateBySig: invalid nonce");
        require(block.timestamp <= expiry, "Alch::delegateBySig: signature expired");
        return _delegate(signatory, delegatee);
    }
    function getCurrentVotes(address account) external view returns (uint96) {
        uint32 nCheckpoints = numCheckpoints[account];
        return nCheckpoints > 0 ? checkpoints[account][nCheckpoints - 1].votes : 0;
    }
    function getPriorVotes(address account, uint256 blockNumber)
    public
    view
    returns (uint96)
    {
        require(
            blockNumber < block.number,
            "Alch::getPriorVotes: not yet determined"
        );
        uint32 nCheckpoints = numCheckpoints[account];
        if (nCheckpoints == 0) {
            return 0;
        }
        if (checkpoints[account][nCheckpoints - 1].fromBlock <= blockNumber) {
            return checkpoints[account][nCheckpoints - 1].votes;
        }
        if (checkpoints[account][0].fromBlock > blockNumber) {
            return 0;
        }
        uint32 lower = 0;
        uint32 upper = nCheckpoints - 1;
        while (upper > lower) {
            uint32 center = upper - (upper - lower) / 2;
            Checkpoint memory cp = checkpoints[account][center];
            if (cp.fromBlock == blockNumber) {
                return cp.votes;
            } else if (cp.fromBlock < blockNumber) {
                lower = center;
            } else {
                upper = center - 1;
            }
        }
        return checkpoints[account][lower].votes;
    }
    function _delegate(address delegator, address delegatee) internal {
        address currentDelegate = delegates[delegator];
        uint96 delegatorBalance = balances[delegator];
        delegates[delegator] = delegatee;
        emit DelegateChanged(delegator, currentDelegate, delegatee);
        _moveDelegates(currentDelegate, delegatee, delegatorBalance);
    }
    function _transferTokens(
        address src,
        address dst,
        uint96 amount
    ) internal {
        require(
            src != address(0),
            "Alch::_transferTokens: cannot transfer from the zero address"
        );
        require(
            dst != address(0),
            "Alch::_transferTokens: cannot transfer to the zero address"
        );
        balances[src] = sub96(
            balances[src],
            amount,
            "Alch::_transferTokens: transfer amount exceeds balance"
        );
        balances[dst] = add96(
            balances[dst],
            amount,
            "Alch::_transferTokens: transfer amount overflows"
        );
        emit Transfer(src, dst, amount);
        _moveDelegates(delegates[src], delegates[dst], amount);
    }
    function _moveDelegates(
        address srcRep,
        address dstRep,
        uint96 amount
    ) internal {
        if (srcRep != dstRep && amount > 0) {
            if (srcRep != address(0)) {
                uint32 srcRepNum = numCheckpoints[srcRep];
                uint96 srcRepOld = srcRepNum > 0
                ? checkpoints[srcRep][srcRepNum - 1].votes
                : 0;
                uint96 srcRepNew = sub96(
                    srcRepOld,
                    amount,
                    "Alch::_moveVotes: vote amount underflows"
                );
                _writeCheckpoint(srcRep, srcRepNum, srcRepOld, srcRepNew);
            }
            if (dstRep != address(0)) {
                uint32 dstRepNum = numCheckpoints[dstRep];
                uint96 dstRepOld = dstRepNum > 0
                ? checkpoints[dstRep][dstRepNum - 1].votes
                : 0;
                uint96 dstRepNew = add96(
                    dstRepOld,
                    amount,
                    "Alch::_moveVotes: vote amount overflows"
                );
                _writeCheckpoint(dstRep, dstRepNum, dstRepOld, dstRepNew);
            }
        }
    }
    function _writeCheckpoint(
        address delegatee,
        uint32 nCheckpoints,
        uint96 oldVotes,
        uint96 newVotes
    ) internal {
        uint32 blockNumber = safe32(
            block.number,
            "Alch::_writeCheckpoint: block number exceeds 32 bits"
        );
        if (
            nCheckpoints > 0 &&
            checkpoints[delegatee][nCheckpoints - 1].fromBlock == blockNumber
        ) {
            checkpoints[delegatee][nCheckpoints - 1].votes = newVotes;
        } else {
            checkpoints[delegatee][nCheckpoints] = Checkpoint(blockNumber, newVotes);
            numCheckpoints[delegatee] = nCheckpoints + 1;
        }
        emit DelegateVotesChanged(delegatee, oldVotes, newVotes);
    }
    function safe32(uint256 n, string memory errorMessage)
    internal
    pure
    returns (uint32)
    {
        require(n < 2**32, errorMessage);
        return uint32(n);
    }
    function safe96(uint256 n, string memory errorMessage)
    internal
    pure
    returns (uint96)
    {
        require(n < 2**96, errorMessage);
        return uint96(n);
    }
    function add96(
        uint96 a,
        uint96 b,
        string memory errorMessage
    ) internal pure returns (uint96) {
        uint96 c = a + b;
        require(c >= a, errorMessage);
        return c;
    }
    function sub96(
        uint96 a,
        uint96 b,
        string memory errorMessage
    ) internal pure returns (uint96) {
        require(b <= a, errorMessage);
        return a - b;
    }
    function getChainId() internal pure returns (uint256) {
        uint256 chainId;
        assembly {
            chainId := chainid()
        }
        return chainId;
    }
}// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <0.8.0;
/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        uint256 c = a + b;
        if (c < a) return (false, 0);
        return (true, c);
    }
    /**
     * @dev Returns the substraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b > a) return (false, 0);
        return (true, a - b);
    }
    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) return (true, 0);
        uint256 c = a * b;
        if (c / a != b) return (false, 0);
        return (true, c);
    }
    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a / b);
    }
    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a % b);
    }
    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");
        return c;
    }
    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a, "SafeMath: subtraction overflow");
        return a - b;
    }
    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        if (a == 0) return 0;
        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");
        return c;
    }
    /**
     * @dev Returns the integer division of two unsigned integers, reverting on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: division by zero");
        return a / b;
    }
    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: modulo by zero");
        return a % b;
    }
    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {trySub}.
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        return a - b;
    }
    /**
     * @dev Returns the integer division of two unsigned integers, reverting with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryDiv}.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        return a / b;
    }
    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting with custom message when dividing by zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryMod}.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        return a % b;
    }
}