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