contract FixedSupplyToken is ERC20Interface {
    using SafeMath for uint256;

    string public symbol;
    string public name;
    uint8 public decimals;

    mapping(address => uint256) public balances;
    mapping(address => mapping(address => uint256)) public allowed;

    modifier onlyPayloadSize(uint size) {
        assert(msg.data.length == size + 4);
        _;
    }

    constructor() public {
        symbol = "MSHM";
        name = "MinSheng Health Main Token";
        decimals = 18;
        totalSupply = 100000000 * 10**uint(decimals);
        balances[msg.sender] = totalSupply;
        emit Transfer(address(0), msg.sender, totalSupply);
    }


    /**
     * Get the token balance for account `tokenOwner`
     */
    function balanceOf(address tokenOwner) public view returns (uint256 balanceOfOwner) {
        return balances[tokenOwner];
    }


    /**
     * Transfer the balance from token owner's account to `to` account
     * - Owner's account must have sufficient balance to transfer
     * - 0 value transfers are allowed
     */
    function transfer(address to, uint256 tokens) onlyPayloadSize(2 * 32) public returns (bool success) {
        require(to != address(0));
        require(tokens <= balances[msg.sender]);

        balances[msg.sender] = balances[msg.sender].sub(tokens);
        balances[to] = balances[to].add(tokens);

        emit Transfer(msg.sender, to, tokens);

        return true;
    }


    /**
     * Token owner can approve for `spender` to transferFrom(...) `tokens`
     * from the token owner's account
     *
     * https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20-token-standard.md
     * recommends that there are no checks for the approval double-spend attack
     * as this should be implemented in user interfaces
     */
    function approve(address spender, uint256 tokens) public returns (bool success) {
        allowed[msg.sender][spender] = tokens;
        emit Approval(msg.sender, spender, tokens);
        return true;
    }


    /**
     * Transfer `tokens` from the `from` account to the `to` account
     *
     * The calling account must already have sufficient tokens approve(...)-d
     * for spending from the `from` account and
     * - From account must have sufficient balance to transfer
     * - Spender must have sufficient allowance to transfer
     * - 0 value transfers are allowed
     */
    function transferFrom(address from, address to, uint256 tokens) onlyPayloadSize(3 * 32) public returns (bool success) {
        require(to != address(0));
        require(tokens <= balances[from]);
        require(tokens <= allowed[from][msg.sender]);

        balances[from] = balances[from].sub(tokens);
        allowed[from][msg.sender] = allowed[from][msg.sender].sub(tokens);
        balances[to] = balances[to].add(tokens);

        emit Transfer(from, to, tokens);

        return true;
    }


    /**
     * Returns the amount of tokens approved by the owner that can be
     * transferred to the spender's account
     */
    function allowance(address tokenOwner, address spender) public view returns (uint256 remaining) {
        return allowed[tokenOwner][spender];
    }


    /**
     * Don't accept ETH
     */
    function () public payable {
        revert();
    }
}
function transfer(address to, uint256 tokens) onlyPayloadSize(2 * 32) public returns (bool success) {
    require(to != address(0));
    require(tokens <= balances[msg.sender]);

    balances[msg.sender] = balances[msg.sender].sub(tokens);
    balances[to] = balances[to].add(tokens);

    emit Transfer(msg.sender, to, tokens);

    return true;
}

/**
 * Transfer the balance from token owner's account to `to` account
 * - Owner's account must have sufficient balance to transfer
 * - 0 value transfers are allowed
 */