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