#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int INF = 1<<30;
const ll INFLL = 1LL<<60;
const int MOD = 998244343;


int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int n; cin >> n;
    vector<int> a(n);
    bool ok = false;
    for (int i = 0; i < n; i++){
        cin >> a[i];
        if (a[i] <= 1) ok = true;
    }
    cout << (ok ? "Yes" : "No") << endl;
    
    return 0;
}