#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n, t, k = 0, m;
  cin >> n >> t;
  m = n;
  while (n > 0) {
    if (m < 2 && t == 10) {
      cout << -1;
      break;
    }
    if (t != 10)
      cout << t;
    else {
      if (k == 0)
        cout << 1, k = 1;
      else
        cout << 0;
    }
    n--;
  }
}
