#include <iostream> #include <cmath> using namespace std; int main() { int n; cin >> n; if (n < 2) { cout << "NO" << endl; return 0; } bool is_prime = true; for (int i = 2; i <= sqrt(n); i++) { if (n % i == 0) { is_prime = false; break; } } if (is_prime) { cout << "YES" << endl; } else { cout << "NO" << endl; } return 0; }