#include <bits/stdc++.h>
using namespace std;
void print(list<int> *gr, int n) {
  for (int i = 1; i < n; ++i) {
    cout << i << "->";
    for (auto nbr : gr[i]) {
      cout << nbr << " ";
    }
    cout << endl;
  }
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n, t;
  cin >> n >> t;
  if (t == 10) {
    if (n == 1) {
      cout << -1 << endl;
      return 0;
    } else {
      cout << 1;
      while (--n) {
        cout << 0;
      }
      return 0;
    }
  }
  while (n--) {
    cout << t;
  }
}
