#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, t;
  cin >> n >> t;
  if (t == 10) {
    if (n == 1) {
      cout << "-1";
      return 0;
    }
    cout << '1';
    for (long long i = 2; i <= n; i++) cout << '0';
  } else
    for (long long i = 1; i <= n; i++) cout << t;
  return 0;
}
