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