;;;;;;;;;;;;;;;;;;;;;;;;;;;
; Implement count system
;;;;;;;;;;;;;;;;;;;;;;;;;;;

; variables
(defparameter *search_que* '(1))
(defparameter *history* '(1))
(defparameter *depth_list* '(1))
(defparameter *depth* 1)
(defparameter *goal_depth_list* '())

(defvar *start* 1)

; functions
(defun n_to_bit (node)
  (count #\1 (format nil "~b" node))
  )

(defun add_node (node n)
  (cond ((or
	   (> node n)
	   (< node *start*)
	   (> (count node *history*) 0))
	 (return-from add_node nil)
	 ))
  (push node *search_que*)
  (push node *history*)
  (push *depth* *depth_list*)
  )

(defun add-neghboring-node (n now)
  ; next
  (add_node (+ now (n_to_bit now)) n)
  ; prev
  (add_node (- now (n_to_bit now)) n)
  )

; add a present node to the que
; pop a node from que or return -1
; return count if a node is the goal
; add neighboring node which isn't searched to the que
(defun loop-count-goal (n)
  (loop 
    (if (<= (length *search_que*) 0)
      (return-from loop-count-goal -1))
    (if (= (car *search_que*) n) 
      (push *depth* *goal_depth_list*))
;      (return-from loop-count-goal *depth*))
    (setf *depth* (1+ (pop *depth_list*)))
    (add-neghboring-node n (pop *search_que*))
    )
  )

(defun n3 ()
  (loop-count-goal (parse-integer (read-line)))
  (cond ((= (length *goal_depth_list*) 0)
	 (princ -1))
	 (t
	 (princ (loop for i in *goal_depth_list*
		      minimize i))))
  )

(n3)