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