#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, t, k, i;
  cin >> n >> t;
  if ((n == 1) and (t == 10))
    cout << -1;
  else {
    if (t == 10) {
      cout << '1';
      t = 0;
      n = n - 1;
    }
    for (i = 0; i < n; i++) cout << t;
  }
}
