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