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