#include <bits/stdc++.h>
using namespace std;
const int DBG = 0;
const int N = 220;
int main() {
  if (DBG) {
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
  }
  int n, t;
  cin >> n >> t;
  if (t == 10) {
    if (n == 1)
      cout << -1;
    else {
      cout << 1;
      for (int i = 1; i < n; i++) cout << 0;
    }
  } else {
    for (int i = 1; i <= n; i++) cout << t;
  }
}
