/*
 * prime.c
 * This program read and integer number and checks whether it is prime.
 */

#include <stdio.h>

int main ()
{
  int     n;
  int     is_prime = 1;
  int     i;

  /* Read the number. */
  printf ("Please enter a positive integer: ");
  scanf ("%d", &n);

  /* Check the input. */
  if (n <= 0)
  {
    printf ("Illegal input!\n");
    return (1);
  }

  /* Check if any of the numbers 2, ... , n-1 divide it. */
  for (i = 2; i < n; i++)
  {
    if (n % i == 0)
    {
      is_prime = 0;
      break;
    }
  }

  /* Print the result. */
  if (is_prime)
    printf ("%d is a prime.\n", n);
  else
    printf ("%d is not a prime.\n", n);

  return (0);
}