// Recursive Euclid's algorithm for greatest common divisor:
//
//      Algorithm: gcd(a,b) = a if b=0, else = gcd (b, a mod b)

// Examples: a=99, b=78:        gcd = 3  = (-11) * 99 + (14) * 78
//           a = 1769, b = 551: gcd = 29 = (5) * 1769 + (-16) * 551

//
// ----------------------------------------------------
//     (c) Copyright 2003  Julian V. Noble.          //
//       Permission is granted by the author to      //
//       use this software for any application pro-  //
//       vided this copyright notice is preserved.   //
// ----------------------------------------------------

#include <math.h>
#include <stdio.h>


int gcd( int m, int n); // prototype

int main(void)
{ 
  int a, b, r;

  printf("What are m and n? ");
  scanf(" %d%d", &a, &b);
  r = gcd(a,b);
  printf( " %d\n", r ) ;
  return 0;
}

  int gcd( int m, int n )   // recursive
  {

    if(n==0)
    {  return m;
    }

    return gcd(n,m%n);
  }