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