private int matchingTokenID(String title) {
        HashSet<Integer> outOfQuestion = new HashSet<>();
        for (int i = this.tokens.size() - 1; i >= 0; --i) {
            Token t = this.tokens.get(i);

            if (t.isText() || outOfQuestion.contains(t.getID()))
                continue;

            if (t.closingTag()) {
                outOfQuestion.add(t.getID());
                continue;
            }

            if (t.getTag().equalsIgnoreCase(title))
                return t.getID();
        }

        return -1;
    }