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