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