#include <iostream>
#include <vector>
using namespace std;

int zero, one;

vector<bool> Eratosthenes(int Num) {
    vector<bool> p(Num, true);
    p[zero] = p[one] = false;
    for (int i = 0; i < Num; ++i)if (p[i])
        for (int j = i << 1; j < Num; j += i)p[j] = false;
    return p;
}

int main() {
  one++;
  int n; cin >> n;
  auto p = Eratosthenes(1005);
  cout << (p[n] ? "YES" : "NO") << endl;
}