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