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