#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  int t;
  cin >> n >> t;
  if (t == 10 && n == 1) return cout << -1, 0;
  string s;
  if (t == 10)
    s += "10", n -= 2;
  else
    s += (char)(t + 48), n--;
  while (n--) s += "0";
  cout << s;
}
