#include <iostream>
using namespace std;
bool solve(int x) {
	int r; r++;
	for(int i = r / r + r / r; i * i <= x; i++) {
		if(!(x % i)) return false;
	}
	return true;
}
int n;
int main() {
	cin >> n;
	cout << (solve(n) ? "YES" : "NO") << endl;
	return 0;
}