#include <bits/stdc++.h>
using namespace std;
bool isFound(long long n, long long k) {}
int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long n, t, power;
  cin >> n >> t;
  if (n == 1 && t == 10)
    cout << -1 << endl;
  else {
    if (t == 10) n--;
    cout << t;
    for (int i = 1; i < n; i++) cout << "0";
  }
  cout << endl;
}
