// C++ 質數判別

//質數判別 
#include<iostream>
#include<cstdlib>
using namespace std;
int main(void)
{
int n;
cout << "Please input a number:" ;
cin >> n;
bool factor=false;
for(int i=2; i<n; i++)
{
if( n%i==0 ) factor=true;
}

if(factor)
cout << endl << "NO" ;
else 
cout << endl << "YES" ;

system("pause");
return 0;
}