/* A program that figures out whther a number is prime or not */

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

int main()
{
  int i, prime, sq;
  printf("Enetr a number: ");
  if (scanf("%d", &prime) != 1) {
    printf("ERROR: failed to read a number!\n");
    return -1;
  }
  sq = (int) sqrt(prime);
  for (i = 2; (i <= sq) && (prime % i != 0); i++);
  if (i > sq)
    printf("%d is prime\n", prime);
  else
      printf("%d is not prime (divided by %d)\n", prime, i);
  return 0;
}