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