#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));
}