/*
 * ISA 563, Spring 2011
 * Copyleft by Muhammad Abdulla
 */


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

/*
 * gcd.c -- calculate the greatest common divisor of two integers
 */

// function declaration
int gcd(int, int);

int main ( int argc, char *argv[] )
{
   int a;
   int b;

   if ( argc != 3 ) {
      fprintf(stderr, "Usage: %s number1 number2\n", argv[0]);
      exit(-1);
   } else {
      a = atoi(argv[1]);
      b = atoi(argv[2]);
   }

   printf("gcd(%d, %d): %d\n", a, b, gcd(a, b));

   return 0;
}

// function definition
int gcd ( int a, int b )
{
   if ( b == 0 ) {
      return a;
   } else {
      return gcd(b, a%b);
   }
}