public class Task12 {

    public ArrayList removeSecondElement(ArrayList list) {
        Iterator iterator = list.iterator();
        while (iterator.hasNext()) {
            if (iterator.next() != (list.get(list.size() - 1))) {
                iterator.next();
                iterator.next();
                iterator.remove();
            } else {
            }
        }

        return list;
    }

    public static void main(String[] args) {
        ArrayList<Integer> list = new ArrayList();

        for (int i = 0; i < 25; i++) {
            list.add(i);
        }

        Task12 task = new Task12();
        while (list.size() != 1) {
           list = task.removeSecondElement(list);
        }

        System.out.println(list);
    }
}

if (iterator.next() != (list.get(list.size() - 1)))