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