#include <iostream>
 #include <iomanip>
 #include <cmath>
 #include <algorithm>
 #include <cstdlib>
 #include <limits.h>
 #include <string>

 #define ll long long

 using namespace std;
 void Fast_IO();
 void Rofyda_Elghadban(){
   #ifndef ONLINE_JUDGE
        freopen("input.txt", "r", stdin), freopen("output.txt", "w", stdout);
    #endif
}
int main()
 {   Rofyda_Elghadban();
 //Fast_IO();
 //freopen("input.txt","r",stdin);
 //freopen("output.txt","r",stdout);
 ll n;
 cin>>n;
 int flag=0;
 if(n>=2){
  for(int i=2;i<=n/2;i++){
    if(n%i==0){
      cout<<"NO"<<endl;
      flag=1;
      break;
     }
 } if(flag==0){
  cout<<"YES"<<endl;
 }
 }else{
  cout<<"NO"<<endl;
 }







 return 0;
 }