private Set<String> getLinkedWords(String s, List<String> words) {
        Set<String> tmp = new HashSet<String>();
        for (int i = 0; i < words.size()-1; i++) {
            if (s.equals(words.get(i))) {
                tmp.add(words.get(i + 1));
            }
        }
        return tmp;
    }