for (int i = 0; i < lessons.size(); i++) {

            String currentElement = lessons.get(i);
            if (currentElement.contains("+ex")) {
                currentElement.replaceAll("\\+ex", "");

                //System.out.println(currentElement.replaceAll("\\+ex","") + "-Exercise");
            }
            System.out.printf("%d.%s%n", i + 1, lessons.get(i));
        }