(define (merge-lists a b)
  (cond  ((and(null? a) (null? b)) '())
         ((and (not (null? a)) (null? b)) a)
         ((and (null? a) (not (null? b))) b)
         (#t
          (if (< (car a) (car b))
              (cons (car a) (merge-lists (cdr a) b))
              (cons (car b) (merge-lists a (cdr b)))))))

(define foo2 '(1 3 4 7))
(define foo1 '(2 5 8 9))



(define (delenie l)
  (delenie-loop '() '() l))

;(define (delenie-loop left right total)
;  (cond [(null? total) (list left right)]
;        [(null? (cdr total)) (list (cons (car total) left) right)]
;        [#t  (delenie-loop (cons (car total) left) (cons (cadr total) right)  (cddr total))]))


(define (delenie-loop left right total)
  (if (null? total)
      (list left right)
      (delenie-loop right (cons (car total) left) (cdr total))))

(display (delenie (list 1 2 3 4 5 6 7)))