long tableOfRemainders(int[] n) {

    long res = 0;
    Arrays.sort(n); // we sort the numbers.
    ArrayList<Integer> hold = new ArrayList<Integer>(); //to shorten calculation between duplicate number, so we count the duplicate number and place it into hold.
    HashSet<Integer> uniqNumber = new HashSet<Integer>(); // create it uniq
    List<Integer> numbers = Arrays.stream(n).boxed().collect(Collectors.toList()); // make it as List to use lastIndexOf.

    for(int i = 0;i < numbers.size();i++) {
        int x = numbers.lastIndexOf(numbers.get(i));
        uniqNumber.add(numbers.get(i));
        hold.add(x-i+1);
        i=x;
    }


    return res;
}