pragma solidity 0.5.9;

/**
 * @title SafeMath 
 * @dev Unsigned math operations with safety checks that revert on error.
 */
library SafeMath {
    /**
     * @dev Multiplie two unsigned integers, revert on overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (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-solidity/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b);

        return c;
    }

    /**
     * @dev Integer division of two unsigned integers truncating the quotient, revert on division by zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        // Solidity only automatically asserts when dividing by 0
        require(b > 0);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Subtract two unsigned integers, revert on underflow (i.e. if subtrahend is greater than minuend).
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a);
        uint256 c = a - b;

        return c;
    }

    /**
     * @dev Add two unsigned integers, revert on overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a);

        return c;
    }
}

/*
 * @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 GSN 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.
 */
contract Context {
    // Empty internal constructor, to prevent people from mistakenly deploying
    // an instance of this contract, which should be used via inheritance.
    constructor () internal { }

    function _msgSender() internal view returns (address payable) {
        return msg.sender;
    }
}

/**
 * @title ERC20 interface
 * @dev See https://eips.ethereum.org/EIPS/eip-20
 */
interface IERC20 {
    function transfer(address to, uint256 value) external returns (bool); 

    function approve(address spender, uint256 value) external returns (bool); 

    function transferFrom(address from, address to, uint256 value) external returns (bool); 

    function totalSupply() external view returns (uint256); 

    function balanceOf(address who) external view returns (uint256);

    function allowance(address owner, address spender) external view returns (uint256); 

    event Transfer(address indexed from, address indexed to, uint256 value); 

    event Approval(address indexed owner, address indexed spender, uint256 value); 
}


/**
 * @title Standard ERC20 token
 * @dev Implementation of the basic standard token.
 */
contract StandardToken is IERC20, Context {
    using SafeMath for uint256; 
    
    mapping (address => uint256) internal _balances; 
    mapping (address => mapping (address => uint256)) internal _allowed; 
    
    uint256 internal _totalSupply; 
    
    /**
     * @dev Total number of tokens in existence.
     */
    function totalSupply() public view returns (uint256) {
        return _totalSupply; 
    }

    /**
     * @dev Get the balance of the specified address.
     * @param owner The address to query the balance of.
     * @return A uint256 representing the amount owned by the passed address.
     */
    function balanceOf(address owner) public view  returns (uint256) {
        return _balances[owner];
    }

    /**
     * @dev Function to check the amount of tokens that an owner allowed to a spender.
     * @param owner The address which owns the funds.
     * @param spender The address which will spend the funds.
     * @return A uint256 specifying the amount of tokens still available for the spender.
     */
    function allowance(address owner, address spender) public view returns (uint256) {
        return _allowed[owner][spender];
    }

    /**
     * @dev Transfer tokens to a specified address.
     * @param to The address to transfer to.
     * @param value The amount to be transferred.
     */
    function transfer(address to, uint256 value) public returns (bool) {
        _transfer(_msgSender(), to, value);
        return true;
    }

    /**
     * @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender.
     * 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
     * @param spender The address which will spend the funds.
     * @param value The amount of tokens to be spent.
     */
    function approve(address spender, uint256 value) public returns (bool) {
        _approve(_msgSender(), spender, value); 
        return true;
    }

    /**
     * @dev Transfer tokens from one address to another.
     * Note that while this function emits an Approval event, this is not required as per the specification,
     * and other compliant implementations may not emit the event.
     * @param from The address which you want to send tokens from.
     * @param to The address which you want to transfer to.
     * @param value The amount of tokens to be transferred.
     */
    function transferFrom(address from, address to, uint256 value) public returns (bool) {
        _transfer(from, to, value); 
        _approve(from, _msgSender(), _allowed[from][_msgSender()].sub(value)); 
        return true;
    }

    /**
     * @dev Increase the amount of tokens that an owner allowed to a spender.
     * approve should be called when _allowed[msg.sender][spender] == 0. To increment
     * allowed value is better to use this function to avoid 2 calls (and wait until
     * the first transaction is mined)
     * From MonolithDAO Token.sol
     * Emits an Approval event.
     * @param spender The address which will spend the funds.
     * @param addedValue The amount of tokens to increase the allowance by.
     */
    function increaseAllowance(address spender, uint256 addedValue) public returns (bool) {
        _approve(_msgSender(), spender, _allowed[_msgSender()][spender].add(addedValue)); 
        return true;
    }

    /**
     * @dev Decrease the amount of tokens that an owner allowed to a spender.
     * approve should be called when _allowed[msg.sender][spender] == 0. To decrement
     * allowed value is better to use this function to avoid 2 calls (and wait until
     * the first transaction is mined)
     * From MonolithDAO Token.sol
     * Emits an Approval event.
     * @param spender The address which will spend the funds.
     * @param subtractedValue The amount of tokens to decrease the allowance by.
     */
    function decreaseAllowance(address spender, uint256 subtractedValue) public returns (bool) {
        _approve(_msgSender(), spender, _allowed[_msgSender()][spender].sub(subtractedValue));
        return true;
    }

    /**
     * @dev Transfer tokens for a specified address.
     * @param from The address to transfer from.
     * @param to The address to transfer to.
     * @param value The amount to be transferred.
     */
    function _transfer(address from, address to, uint256 value) internal {
        require(to != address(0), "Cannot transfer to the zero address"); 
        _balances[from] = _balances[from].sub(value); 
        _balances[to] = _balances[to].add(value); 
        emit Transfer(from, to, value); 
    }

    /**
     * @dev Approve an address to spend another addresses' tokens.
     * @param owner The address that owns the tokens.
     * @param spender The address that will spend the tokens.
     * @param value The number of tokens that can be spent.
     */
    function _approve(address owner, address spender, uint256 value) internal {
        require(spender != address(0), "Cannot approve to the zero address"); 
        require(owner != address(0), "Setter cannot be the zero address"); 
	    _allowed[owner][spender] = value;
        emit Approval(owner, spender, value); 
    }

    /**
     * @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 {
        require(account != address(0), "ERC20: burn from the zero address");
        _balances[account] = _balances[account].sub(amount);
        _totalSupply = _totalSupply.sub(amount);
        emit Transfer(account, address(0), amount);
    }

    /**
     * @dev Destroys `amount` tokens from `account`.`amount` is then deducted
     * from the caller's allowance.
     *
     * See {_burn} and {_approve}.
     */
    function _burnFrom(address account, uint256 amount) internal {
        _burn(account, amount);
        _approve(account, _msgSender(), _allowed[account][_msgSender()].sub(amount));
    }

}

/**
 * @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.
 *
 * 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.
 */
contract Ownable is Context {
    address internal _owner;

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

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

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(isOwner(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Returns true if the caller is the current owner.
     */
    function isOwner() public view returns (bool) {
        return _msgSender() == _owner;
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public onlyOwner {
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     */
    function _transferOwnership(address newOwner) internal {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

contract GCToken is StandardToken, Ownable {
    string public constant name = "GameChain";
    string public constant symbol = "GC";
    uint8 public constant decimals = 18;
    
    uint256 internal constant INITIAL_SUPPLY = 5000000000 ether;
    uint256 internal constant lock_total = 250000000 ether;            
    uint256 private start_time;
    uint256 private one_year = 31536000;    

    uint256 private release_value = 50000000 ether;
    address private constant tokenWallet = 0x0F8526f916f6CeCafF32ECbb52D9Cc17007D5BDF;
    address private constant team_address = 0x815e727a5741fF2eeFDf3A373D42F68AE71691FC;
    address private constant foundation_address = 0xA48EA7cFfC41bf0161E23ecc25CA72FC871B68D7;
    event Lock(address account, uint lock_total);
    
    /**
     * @dev Constructor, initialize the basic information of contract.
     */
    constructor() public {
        _totalSupply = INITIAL_SUPPLY;
        _owner = tokenWallet;
        _balances[_owner] = 4500000000 * 10 ** uint(decimals);
        start_time = now.add(one_year*2);
        _lock(team_address);
        _lock(foundation_address);
        emit Transfer(address(0), _owner, 4500000000 * 10 ** uint(decimals));
    }
    function _lock(address account) internal {
        _balances[account] = _balances[account].add(lock_total);
        emit Transfer(address(0), account, lock_total);
    }

    function transfer(address _to, uint256 _value) public returns (bool) {
        if (msg.sender == team_address || msg.sender == foundation_address) {
            uint256 extra = getLockBalance();
            require(_balances[_msgSender()].sub(_value) >= extra);
        }
        return super.transfer(_to, _value);
        
    }
    function transferFrom(address _from, address _to, uint256 _value) public returns (bool) {
        if (_from == team_address || _from == foundation_address) {
        uint256 extra = getLockBalance();
        require(_balances[_from].sub(_value) >= extra);
        }
        return super.transferFrom(_from, _to, _value);
    }
     function getLockBalance() public view returns(uint) {
         if (now < start_time) {
             return lock_total;
         }
        uint256 value = release_value.mul(((now.sub(start_time)).div(31536000)).add(1));
        if (value >= lock_total) {
            return 0;
        } 
        return lock_total.sub(value);   
    }

    function burn(uint256 amount) public onlyOwner {
        _burn(msg.sender, amount); 
    }

    /**
     * @dev See {ERC20-_burnFrom}.
     */
    function burnFrom(address account, uint256 amount) public onlyOwner {
        _burnFrom(account, amount); 
    }
}

{
  "compilationTarget": {
    "GCToken.sol": "GCToken"
  },
  "evmVersion": "petersburg",
  "libraries": {},
  "optimizer": {
    "enabled": false,
    "runs": 200
  },
  "remappings": []
}