#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, t;
  cin >> n >> t;
  if (t != 10) {
    for (int i = 0; i < n; ++i) {
      cout << t;
    }
  } else if (n == 1)
    cout << -1;
  else {
    for (int i = 0; i < n - 1; ++i) {
      cout << '1';
    }
    cout << '0';
  }
}
