#include <bits/stdc++.h>
using namespace std;
const int N = 1000050;
int a[N];
int main() {
  int n, k;
  cin >> n >> k;
  if (n == 1 && k == 10)
    cout << "-1" << endl;
  else {
    if (k == 10) {
      cout << "1";
      for (int i = 1; i < n; i++) cout << "0";
      cout << endl;
    } else {
      for (int i = 0; i < n; i++) cout << k;
      cout << endl;
    }
  }
  return 0;
}
