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