final

(defun ortak (list1 list2)
    (cond 
        ((null list1) nil)
        ((member (car list1) list2)(append (list (car list1)) (ortak (cdr list1) list2))  )
        (t   (ortak (cdr list1) list2))
    )
)
(setq a '(2 10 4))
(setq b '(1 2 3 4 5 6))
(write (ortak a b))
(terpri)

(defun add (list1 elem)
    (cond
        ((null list1) (append (list elem)))
        ((< elem (car list1)) (append (list elem) list1))
        (t (append (list (car list1)) (add (cdr list1) elem)))
    )
)
(write (add b 7))
(terpri)
(defun sortt (list1 &optional list2)
    (cond 
        ((null list1) list2)
        ((null list2) (sortt (cdr list1) (list (car list1))))
        (t (setq list2 (add list2 (car list1))) (sortt (cdr list1) list2) )
    )
)
(write (sortt a))