#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using ll = long long;

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n, cnt = 0;
    cin >> n;
    vector<int> a(n);
    for(auto &&v : a) cin >> v;
    cout << (*min_element(a.begin(), a.end()) <= 1 ? "Yes" : "No") << '\n';
}