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