#include <stdio.h>
#include <stdlib.h>

unsigned long mcd (unsigned long a, unsigned long b)
{
  while (1) {
    if (a==b) return a;
    else if (a > b) a = a - b;
    else b = b - a;
  }
}

main(int argc,char **argv) 
{
  unsigned long a = (unsigned long) atol(argv[1]);
  unsigned long b = (unsigned long) atol(argv[2]);
  printf("mcd(%ld,%ld) = %ld\n",a,b,mcd(a,b));
}