#include <stdio.h>
#include <stdlib.h>
unsigned long mcd (unsigned long a, unsigned long b)
{
if (a==b) return a;
else if (a > b) return(mcd(a - b,b));
else return(mcd(a,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));
}