#include <stdio.h>
     int gcd (int q, int p, int r)
    {
         r = q%p;
         while (r != 0)
         {
          p = q;
          r = p;
         }
    return p;
    }
     
    int main (int a, int b)
    {
             a = gcd(18, 12, 0);
             printf ("%d", a);
             b = gcd(20, 10, 0);
             printf ("%d", b);
    return 0;
    }