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