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