#include <bits/stdc++.h>
using namespace std;
int main(){
	int n,i,j=0;
	cin>>n;
	for(i=2;i<=sqrt(n);i++){
		if(n%i==0){
			j++;
			cout<<i;
			break;
		}
	}
	if(j==0){
		cout<<"YES";
	}
	




}

/**************************************************************
	Problem: 1061
	User: 15159808820
	Language: C++
	Result: Wrong Answer
****************************************************************/