#include <iostream>

int zero;
int two;

bool isP(int n) {
	if (n < two) return false;
	for (int i = two; i * i <= n; ++i) {
		if (n % i == zero) return false;
	}
	return true;
}

signed main() {
	++two;
	++two;
	int n;
	std::cin >> n;
	std::cout << ((isP(n) ? "YES" : "NO")) << std::endl;
	return zero;
}