#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, t;
  cin >> n >> t;
  if (n == 1 && t == 10)
    cout << -1;
  else {
    cout << t;
    if (t < 10)
      for (int i = 0; i < n - 1; ++i) cout << 0;
    else
      for (int i = 0; i < n - 2; ++i) cout << 0;
  }
}
