#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  int l;
  cin >> l;
  string s;
  cin >> s;
  if (s.length() % l != 0) {
    string pattern(l, '0');
    pattern[0] = '1';
    int times = s.length() / l + 1;
    while (times-- > 0) {
      cout << pattern;
    }
  } else {
    string pattern = s.substr(0, l);
    int times = s.length() / l;
    string presumablyAnswer;
    for (int i = 0; i < times; ++i) {
      presumablyAnswer += pattern;
    }
    if (presumablyAnswer > s) {
      cout << presumablyAnswer << endl;
    } else {
      if (count(pattern.begin(), pattern.end(), '9') < l) {
        int i = (int)pattern.size() - 1;
        while (pattern[i] == '9') {
          pattern[i] = '0';
          --i;
        }
        ++pattern[i];
        for (int i = 0; i < times; ++i) {
          cout << pattern;
        }
      } else {
        fill(pattern.begin(), pattern.end(), '0');
        pattern[0] = '1';
        for (int i = 0; i <= times; ++i) {
          cout << pattern;
        }
      }
    }
  }
  return 0;
}
