#include <bits/stdc++.h>

#define fast ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define ll long long
#define ull unsigned long long
#define  ld long double
#define no "NO"
#define yes "YES"
#define forr(n) for(int i = 0;i < n; i++)
#define d(n) cout<<"value of "<<#n<<" is "<<n<<endl
#define endl '\n'
using namespace std;
const int N = 1e6 + 5, mode = 1e9 + 7;


void Code() {
    int n;
    string s;
    cin >> n >> s;

    string tmp = "";
    for (int i = 1; i <= n; i++) {
        tmp += to_string(i);
    }

    for (int i = 0; i < s.size(); i++) {
        if (s[i] != tmp[i]) {
            if (i > 8)
                cout << tmp[i - 1];
            cout << tmp[i];
            return;
        }
    }

    cout << n;
}


int main() {
    fast
    int tc = 1;
//    cin >> tc;

    while (tc--)
        Code();
}