/* L-27 MCS 572 Friday 17 March 2006 : interactive prime tester */

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

int is_prime ( int n );
/* 
 * DESCRIPTION :
 *   Returns 0 if n is a prime,
 *   otherwise a divisor of n is returned. */

int main ( int argc, char *argv[] )
{
   int n,d;

   printf("Give a natural number : "); scanf("%d",&n);
   d = is_prime(n);
   if(d == 0)
      printf("The number %d is a prime number.\n",n);
   else
      printf("The number %d is divisible by %d.\n",n,d);

   return 0;
}

int is_prime ( int n )
{
   int i;

   for(i=2; i<n; i++)
      if (n%i == 0) return i;

   return 0;
}