#include "bits/stdc++.h"
//#define int long long
using namespace std;
using ll = long long;
using P = pair<ll, ll>;
const ll INF = (1LL << 61);
ll mod = 1000000007;

signed main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	ll N; cin >> N;
	if (N <= 2)cout << "YES" << endl;
	else cout << "NO" << endl;
	return 0;
}