#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, t;
  cin >> n >> t;
  if (n == 1 && t == 10) {
    cout << -1 << endl;
    return 0;
  }
  if (t == 10) {
    cout << 10;
    n -= 2;
    while (n--) cout << 0;
    return 0;
  }
  while (n--) cout << t;
  return 0;
}
