/* File: p6test12.c

   Use Euclid Algorithm for greatest common divisors (gcd) to 
   check that recursive function calls and the return
   statement works.
*/

#include <stdio.h>

int gcd (int a, int b) {

   int remainder, quotient ;

   if (a < 0 || b < 0) {
      printf("Don't use negative numbers!!!\n") ;
      return -1 ;
   }

   if (b == 0 ) {
      printf ("gcd(%d, %d) = ", a, b) ;
      return a ;
   }

   quotient = a / b ;  /* note: integer division */
   remainder = a - quotient * b ;
   printf("gcd(%d, %d) = ", a, b) ;
   return gcd(b, remainder) ;
}


main() {
   int n, m, g ;
   
   printf("Enter first number: ") ;
   scanf("%d", &n) ;

   printf("Enter second number: ") ;
   scanf("%d", &m) ;

   g = gcd(n,m) ;
   printf ("%d\n", g)  ;
}