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