sicp exercise 2.25

;  Exercise 2.25. Give combinations of cars and cdrs that will pick 7 from each of the following lists:
;  (1 3 (5 7) 9)
;  ((7))
;  (1 (2 (3 (4 (5 (6 7))))))


(define x  '(1 3 (5 7) 9))
(define xx (list 1 3 (list 5 7) 9) )
(define y  '((7)))
(define yy (list (list 7)))
(define z  '(1 (2 (3 (4 (5 (6 7)))))))
(define zz  (list 1 (list 2 (list 3 (list 4 (list 5 (list 6 7))))))) 


(display x)  (newline)
(display xx)  (newline)
(display y)  (newline)
(display yy)  (newline)
(display z)  (newline)
(display zz)  (newline)

(display  (car ( cdr ( car (cdr (cdr xx))))))  (newline)
(display  ( car ( car  yy)))  (newline)
(display (car (cdr (car (cdr (car (cdr (car (cdr (car (cdr (car (cdr zz))))))))))))) (newline)