#include<iostream> 
#include<cmath> 
using namespace std; 

bool IsPrim(int a)
{
 int n = (int)sqrt((double)a);
 for (int i = 2; i <= n; ++i)
 {
  if (a % i == 0)
  {
   return false;
  }
 }
 return true;
}
int main() 
{ 
 int a;
 cout<<"enter a positive integer number"<<endl; 
 cin>>a; 
 if (IsPrim(a))
 {
  cout << a << "是素数！" << endl;
 }
 else
 {
  cout << a << "不是素数!" << endl;
 }
 return 0; 
}