#include <bits/stdc++.h>

using namespace std;

#ifdef LOCAL
#include "../algo/debug.hpp"
#else
#define debug(...) void(0)
#endif

void solve() {
    int n; cin >> n;
    vector<int> a(n);
    for(int i = 0; i < n; i++) cin >> a[i];
    int mn = *min_element(a.begin(), a.end());
    if(mn <= 1) {
        cout << "Yes" << endl;
    }else {
        cout << "No" << endl;
    }
}

int main() {
    int T = 1;
    // cin >> T;
    while (T--) {
        solve();
    }
    return 0;
}