#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long n, t;
  cin >> n >> t;
  if (n == 1 && t == 10) {
    cout << -1 << endl;
    return 0;
  }
  if (t == 10) t = 1;
  cout << t;
  for (long long i = 2; i <= n; i++) {
    cout << 0;
  }
}
