#include <stdio.h>
int main()
 {int n,i;
  printf("please enter a integer number,n=?");
  scanf("%d",&n);
  for (i=2;i<=n-1;i++)
    if(n%i==0) break;
  if(i<n) printf("%d is not a prime number.\n",n);
  else printf("%d is a prime number.\n",n);
  return 0;
}