#include <bits/stdc++.h>
using namespace std;

#define zedanov                   \
    ios_base::sync_with_stdio(0); \
    cin.tie(0);                   \
    cout.tie(0);
#define ll long long
#define el "\n"

void doWork()
{
    int n;
    string a;
    cin >> n;
    cin >> a;
    int cur = 1;
    for (int i = 0; i < a.size(); i++, cur++)
    {
        if (cur < 10)
        {
            if (cur != (a[i] - '0'))
            {
                cout << cur;
                return;
            }
        }
        else if (cur < 100)
        {
            if (i + 1 >= a.size() || cur != stoi(a.substr(i, 2)))
            {
                cout << cur;
                return;
            }
        }
        else
        {
            if (i + 2 >= a.size() || cur != stoi(a.substr(i, 3)))
            {
                cout << cur;
                return;
            }
        }
    }
    cout << cur;
}

signed main()
{
    zedanov int t = 1;
    // cin >> t;
    while (t--)
        doWork();

    return 0;
}