#include <bits/stdc++.h>
using namespace std;
int main() {
  cout.sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cerr.tie(0);
  cout << setprecision(16);
  string S;
  int N;
  while (cin >> N >> S) {
    if (S.size() == 1) {
      cout << S << endl;
      continue;
    }
    cout << '1';
    for (auto i : S)
      if (i == '0') cout << i;
    cout << endl;
  }
}
