#include <bits/stdc++.h>
using namespace std;

bool nt(long long n) {
    if (n <= 1) return false;
    if (n == 2 || n == 3) return true;
    if (n % 2 == 0 || n % 3 == 0) return false;
    for (long long i = 5; i * i <= n; i += 6) {
        if (n % i == 0 || n % (i + 2) == 0) return false;
    }
    return true;
}

int main() {
    ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);
    long long n; cin >> n;
    cout << (nt(n) ? "YES" : "NO");
    return 0;
}