#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, t;
  cin >> n >> t;
  if (t == 10 && n == 1) {
    cout << "-1";
  } else {
    cout << t;
    int dig = 0;
    for (; t > 0; t /= 10, ++dig)
      ;
    for (int i = dig + 1; i <= n; ++i) {
      cout << "0";
    }
  }
  cout << "\n";
  return 0;
}
