library SafeMath {

    /*
        @return sum of a and b
    */
    function ADD (uint256 a, uint256 b) pure internal returns (uint256) {
        uint256 c = a + b;
        assert(c >= a);
        return c;
    }

    /*
        @return difference of a and b
    */
    function SUB (uint256 a, uint256 b) pure internal returns (uint256) {
        assert(a >= b);
        return a - b;
    }
    
}
function ADD (uint256 a, uint256 b) pure internal returns (uint256) {
    uint256 c = a + b;
    assert(c >= a);
    return c;
}

/*
 @return sum of a and b
 */