#lang sicp

(define (dr-aux x acc)
  (if (null? x)
      acc
      (let ((head (car x))
            (tail (cdr x)))
        (if (pair? head)
	  (dr-aux tail
		  (cons (deep-reverse head)
			acc))
	  (dr-aux tail
		  (cons head acc))))))
(define (deep-reverse x)
  (dr-aux x '()))