#include "testlib.h"
#include <bits/stdc++.h>
using namespace std;
using ll = long long;

const ll min_n = 1;
const ll max_n = 200'000;

const string contain_s = "01";

int main(){
    registerValidation();

    ll n = inf.readLong(min_n, max_n);
    inf.readEoln();

    string s = inf.readString();
    inf.readEof();

    assert((int)s.size() == n);
    for (int i = 0; i < n; i++) {
        assert(contain_s.find(s[i]) != string::npos);
    }

}