#include <iostream>
#include <vector>
#include <string>
#include <cstring>
#include <algorithm>
#include <sstream>
#include <map>
#include <set>
using namespace std;


#define REP(i,a,b) for(i=a;i<b;i++)
#define rep(i,n) REP(i,0,n)

typedef long long ll;
typedef unsigned long long ull;
typedef long double lb;
/* ここからが本編 */

int main(void)
{
   ull i,j,k;
   ull n;
   char no = 1;
   cin >> n;
   if(n <= 2) no = 1;
   else {
      for(j=2;j*j<=n;j++)
      {
         if(n%j==0)
         {
            no--;
         }
         if(no == 0) break;
      }
   }
   if(no == 0) cout << "YES" << endl;
   else cout << "NO" << endl;

   return 0;
}