public static LinkedList<String> computeDifference(LinkedList<String> A, LinkedList<String> B)
    {
        LinkedList<String> diff = new LinkedList<String>();
        for(int i =0; i<A.size(); i++)
        {
            String item = A.get(i);
            if(!B.contains(item))
            {
                diff.add(item);
            }
        }
        return diff;
    }