/* greatest common divisor - Euclidean algorithm
   input:  x and y.
   output: greatest common divisor of x and y.
*/
#include <stdio.h>

int main()
{
   int x, y;   /* input */
   int r;

   printf("input: ");
   scanf("%d%d", &x, &y);
   printf("GCD(%d, %d) = ", x, y);

   while (y > 0) {
      r = x % y;
      x = y;
      y = r;
   }

   printf(" %d\n", x);
   return 0;
}