Compare 2 big number [THCS4 N1]

//Tran Viet Anh - 9:43PM
int compare(string x, string y)
{
    if (x.length() > y.length()) return 1;
    else
        if (x.length() < y.length()) return -1;
        else
        {
            for (int i = 0; i < x.length(); i++)
                if (x[i] > y[i]) return 1;
                else if (x[i] < y[i]) return -1;
            return 0;
        }
}