#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, t;
  cin >> n >> t;
  if (n == 1 && t == 10)
    cout << "-1";
  else {
    if (t == 10)
      if (n == 2)
        cout << t;
      else {
        cout << t;
        for (int i = 3; i <= n; i++) cout << '0';
      }
    else {
      cout << t;
      for (int i = 2; i <= n; i++) cout << '0';
    }
  }
  cin >> n;
  return 0;
}
