#include <stdio.h>
#include <stdlib.h>
 
int prime_local(int n, int m) {
  div_t d;
  return ((d = div(n, m)).rem == 0) ? 0 : (d.quot < m) ? 1 : prime_local(n, m + 1);
}
 
int prime(int n) { return (n == 1) ? 0 : (n == 2) ? 1 : (prime_local(n, 2)); }
 
int main() {
  int n;
 
#if 1
  do { printf("n = \n"); scanf("%d", &n);
  } while (n <= 0);
#else
  for (n = 2; n < 100; n++)
#endif
  printf((prime(n) ? "%d prime number.\n" : "%d not prime\n"), n);
  return 0;
}
/* end */
 

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