#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  int n, t;
  cin >> n >> t;
  if (t < 10) {
    cout << t;
    for (int i = 0; i < (int)n - 1; ++i) cout << "0";
  } else {
    if (n == 1)
      cout << -1;
    else if (n == 2)
      cout << 10;
    else {
      cout << 1;
      for (int i = 0; i < (int)n - 1; ++i) cout << 0;
    }
  }
  return 0;
}
