#include <bits/stdc++.h>
#include <atcoder/all>
using ll = long long;
#define MOD 1000000007
#define Mod 998244353
const int MAX = 1000000005;
const long long INF = 1000000000000000005LL;
using namespace std;
using namespace atcoder;



int main() {
    ios::sync_with_stdio(0);cin.tie();
    int N;
    cin >> N;
    vector<int> A(N);
    for (int i = 0; i < N; i++) cin >> A[i];
    for (int i = 0; i < N; i++) {
        if (A[i] == 0 || A[i] == 1) {
            cout << "Yes" << endl;
            return 0;
        }
    }
    cout << "No" << endl;
}