#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, t;
  cin >> n >> t;
  if (n == 1 && t == 10) {
    cout << "-1" << endl;
    return 0;
  }
  cout << ((t == 10) ? 1 : t);
  while (n-- > 1) {
    cout << "0";
  }
  return 0;
}
