#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  string s;
  cin >> s;
  if (n < s.size()) {
    cout << -1 << endl;
  } else {
    cout << s;
    for (int i = 0; i < n - s.size(); i++) {
      cout << 0;
    }
    cout << endl;
  }
  return 0;
}
