// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

contract ERC20 {
    mapping(address => uint256) private _balances;
    mapping(address => mapping(address => uint256)) private _allowances;
    uint256 private _totalSupply;
    string private _name;
    string private _symbol;
    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);
    constructor(string memory name_, string memory symbol_) {
        _name = name_;
        _symbol = symbol_;
    }

    function name() public view virtual  returns (string memory) {
        return _name;
    }

    function symbol() public view virtual  returns (string memory) {
        return _symbol;
    }

    function decimals() public view virtual  returns (uint8) {
        return 18;
    }

    function totalSupply() public view virtual  returns (uint256) {
        return _totalSupply;
    }

    function balanceOf(address account) public view virtual  returns (uint256) {
        return _balances[account];
    }

    function transfer(address to, uint256 amount) public virtual  returns (bool) {
        address owner = msg.sender;
        _transfer(owner, to, amount);
        return true;
    }

    function allowance(address owner, address spender) public view virtual  returns (uint256) {
        return _allowances[owner][spender];
    }

    function approve(address spender, uint256 amount) public virtual  returns (bool) {
        address owner = msg.sender;
        _approve(owner, spender, amount);
        return true;
    }

    function transferFrom(address from, address to, uint256 amount) public virtual  returns (bool) {
        address spender = msg.sender;
        _spendAllowance(from, spender, amount);
        _transfer(from, to, amount);
        return true;
    }

    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        address owner = msg.sender;
        _approve(owner, spender, allowance(owner, spender) + addedValue);
        return true;
    }

    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        address owner = msg.sender;
        uint256 currentAllowance = allowance(owner, spender);
        require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
        unchecked {
            _approve(owner, spender, currentAllowance - subtractedValue);
        }

        return true;
    }

    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");

        uint256 fromBalance = _balances[from];
        require(fromBalance >= amount, "ERC20: transfer amount exceeds balance");
        unchecked {
            _balances[from] = fromBalance - amount;

            _balances[to] += amount;
        }

        emit Transfer(from, to, amount);

    }

    function _mint(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: mint to the zero address");

        _totalSupply += amount;
        unchecked {

            _balances[account] += amount;
        }
        emit Transfer(address(0), account, amount);
    }

    function _burn(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: burn from the zero address");

        uint256 accountBalance = _balances[account];
        require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
        unchecked {
            _balances[account] = accountBalance - amount;

            _totalSupply -= amount;
        }

        emit Transfer(account, address(0), amount);
    }

    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);
    }

    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);
            }
        }
    }

}

pragma solidity ^0.8.19;

contract ForCZ is ERC20 {
    address constant public BINANCE_COLD_WALLET=0xBE0eB53F46cd790Cd13851d5EFf43D12404d33E8;
    uint256 constant DROP_AMOUNT=4000*1e18;

    uint256 constant public TOTAL_SUPPLY=DROP_AMOUNT*10000*2;
    mapping (address => bool) claimed;
    address[] CZSupporters;
    uint256 curTime;
    constructor() ERC20("ForCZ", "FCZ") {
        curTime=block.timestamp;
    }

     fallback () external payable{
        require(msg.sender==tx.origin);
        require(!claimed[msg.sender]);
        
        claimed[msg.sender]=true;
        CZSupporters.push(msg.sender);

        _mint(msg.sender, DROP_AMOUNT);
        _mint(BINANCE_COLD_WALLET,DROP_AMOUNT);

        if(block.timestamp>curTime+4 minutes)
        {
            uint256 you=uint256(blockhash(block.number-1)) % CZSupporters.length;
            _mint(CZSupporters[you], DROP_AMOUNT*4);
            curTime=block.timestamp;
        }
        require(totalSupply()<=TOTAL_SUPPLY);
    }
}