class Kontener {
}

class Element{

    Kontener value;
    Element next;

    public Element(Kontener value){
        this.value = value;
    }
}

class KontenerList{

    Element first;
    int size;

    private final static int limit = 5;

    public void addLast(Kontener k){

        if (size == limit) return;

        if( first == null)
            first = new Element(k);
        else {
            Element tmp = first;

            while(tmp.next != null)
                tmp = tmp.next;

            tmp.next = new Element(k);
        }

        size++;
    }

    Kontener deleteLast() {

        if (size == 0) return null;

         Element beforeLast = first;

         for (int j = 1; j < size-1; j++)
             beforeLast = beforeLast.next;

         Element last = beforeLast.next;

         size--;

         if (last != null) {
             beforeLast.next = null;
             return last.value;
         } else {
             first = null;
             return null;
         }
    }
}