GreatestCommonDivisorCGD

using System;

class GreatestCommonDivisorCGD
{
    static void Main()
    {
        int a = int.Parse(Console.ReadLine());
        int b = int.Parse(Console.ReadLine());

        while (b != 0)
        {
            int oldB = b;
            b = a % b;
            a = oldB;
        }
        Console.WriteLine("GCD = {0}", a);

    }
}