#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int INF = 1e9 + 10;
const ll INFL = 4e18;

int main() {
    int N;
    cin >> N;
    vector<ll> A(N);
    for (int i = 0; i < N; i++) cin >> A[i];

    bool ok = false;
    for (int i = 0; i < N; i++) ok |= A[i] <= 1;

    if (ok) cout << "Yes" << endl;
    else cout << "No" << endl;
}