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