#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; i++)
      if (i == (n - 1))
        cout << 0;
      else
        cout << 1;
  return 0;
}
