#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b, cnt = 0;
  cin >> a >> b;
  int c = b;
  while (c > 0) {
    cnt++;
    c = c / 10;
  }
  if (a == 1 && cnt == 1)
    cout << b;
  else if (cnt > a)
    cout << -1;
  else {
    cout << b;
    a--;
    if (b == 10) a--;
    while (a--) cout << 0;
  }
}
