(defun REMOVE(a l)
 (cond
  ((null l) nil)
  ((EQL a (CAR l)) (REMOVE a (CDR l)) )
  (1 (CONS (CAR l) (REMOVE a (CDR l))) )
 )
)


(defun SORT(a)
 (cond
  ((null a) nil)
  ( 1 (CONS (CAR a) (SORT (REMOVE (CAR a) (CDR a)))) )
 )
)

(SORT '(A B C B D B E))
(SORT '(A B C B A D))
(system)