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