public static int luckBalance(int k, List<List<Integer>> contests) {
  int balance = 0;
  Collections.sort(contests, new Comparator<List<Integer>>() {
    @Override
    public int compare(List<Integer> o1, List<Integer> o2) {
      return o1.get(0).compareTo(o2.get(0));
    }
  });
  int n = contests.size();
  for (int i = n - 1; i >= 0; i--) {
    int current = contests.get(i).get(0);
    if (contests.get(i).get(1) == 1) {
      if (k > 0) {
        balance += current;
        k--;
      } else {
        balance -= current;
      }

    } else {
      balance += current;
    }
  }

  return balance;
}