public long getGCD(long u, long v)
        {
            //may want to add a Thread.Sleep just to slow it down to simulate long calculation
            long gcd = 0;

            u = Math.Abs(u);
            v = Math.Abs(v);
            if (v == 0)
            {
                gcd = u;
            }
            else
            {
                gcd = getGCD(v, u % v);
            }
            return gcd;
        }