#include <bits/stdc++.h>
using namespace std;

int main() {
    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());
    cout << ((mn == 0 || mn == 1) ? "Yes" : "No") << endl;
}