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