#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(false);
  int n, t;
  cin >> n >> t;
  if (n == 1 && t == 10) {
    cout << "-1\n";
  } else if (t == 10) {
    cout << t;
    for (int i = 0; i < n - 2; ++i) {
      cout << '0';
    }
    cout << '\n';
  } else {
    cout << t;
    for (int i = 0; i < n - 1; ++i) {
      cout << '0';
    }
    cout << '\n';
  }
  return 0;
}
