#include <iostream>
using namespace::std;
signed main(void){
	int N;
	cin >> N;
	int i= N-N;
	++i;
	if( N == i ){
		cout << "NO" << endl;
	}else{
		bool flag = false;
		++i;
		for(;i*i<=N && flag==false;++i){
			if( !(N%i) ){
				flag = true;
				cout << "NO" << endl;
			}
		}
		if( flag == false){
			cout << "YES" << endl;
		}
	}
}