#include <bits/stdc++.h>
using namespace std;
const unsigned long long int MAX = 1e13;
const unsigned long long int MIN = 1e-13;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int n, t;
  cin >> n >> t;
  int arr[n];
  memset(arr, 0, sizeof(arr));
  if (t == 10) {
    if (n == 1) return cout << -1, 0;
    arr[0] = 1;
  } else
    arr[0] = t;
  for (int i = 0; i < n; i++) cout << arr[i];
  return 0;
}
