#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;
using ll = long long;

int main() {
    int n;
    string s;
    cin >> n >> s;

    if (n >= 3 || s == "00" || s == "11")cout << "YES" << endl;
    else cout << "NO" << endl;
    return 0;
}