#include <iostream>
using namespace std;

int n;
int a;

int main() {
	cin >> n;
	
	a++;
	if (n == a) {
		cout << "NO" << endl;
		return false;
	}
	a++;
	
	for (int i = a; i * i <= n; i++) {
		if (n % i == false) {
			cout << "NO" << endl;
			return false;
		}
	}
	
	cout << "YES" << endl;
	return false;
}