#include "bits/stdc++.h"

#define ALL(a) (a).begin(),(a).end()
#define SORT(c) sort((c).begin(),(c).end())
#define DESCSORT(c) sort(c.begin(), c.end(), greater<int>())

using namespace std;

using LL = long long int;
using LD = long double;

using pii = pair<int, int>;
using pll = pair<LL, LL>;
using pdd = pair<double, double>;
using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vl = vector<LL>;
using vvl = vector<vl>;
using vvvl = vector<vvl>;
using vd = vector<double>;
using vvd = vector<vd>;
using vs = vector<string>;
using vb = vector<bool>;
using vvb = vector<vb>;

int gcd(int x, int y) { return y ? gcd(y, x % y) : x; }
LL gcd(LL x, LL y) { return y ? gcd(y, x % y) : x; }

int i, zero, one, two, three;

bool isPrime(int n) {
	if (n == one) {
		return false;
	} else if (n == two) {
		return true;
	}

	if (n % two == zero) {
		return false;
	}

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

	return true;
}

int main() {
	one++;
	two++; two++;
	three++; three++; three++;

	int n;
	cin >> n;

	cout << (isPrime(n) ? "YES" : "NO") << endl;
}