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