#-swank
(unless (member :child-sbcl *features*)
  (quit
   :unix-status
   (process-exit-code
    (run-program *runtime-pathname*
                 `("--control-stack-size" "128MB"
                   "--noinform" "--disable-ldb" "--lose-on-corruption" "--end-runtime-options"
                   "--eval" "(push :child-sbcl *features*)"
                   "--script" ,(namestring *load-pathname*))
                 :output t :error t :input t))))
(eval-when (:compile-toplevel :load-toplevel :execute)
  (sb-int:defconstant-eqx OPT
    #+swank '(optimize (speed 3) (safety 2))
    #-swank '(optimize (speed 3) (safety 0) (debug 0))
    #'equal)
  #+swank (ql:quickload '(:cl-debug-print :fiveam) :silent t)
  #-swank (set-dispatch-macro-character
           ;; enclose the form with VALUES to avoid being captured by LOOP macro
           #\# #\> (lambda (s c p) (declare (ignore c p)) `(values ,(read s nil nil t)))))
#+swank (cl-syntax:use-syntax cl-debug-print:debug-print-syntax)
#-swank (disable-debugger) ; for CS Academy

;; BEGIN_INSERTED_CONTENTS
(declaim (inline println-sequence))
(defun println-sequence (sequence &key (out *standard-output*) (key #'identity))
  (let ((init t))
    (sequence:dosequence (x sequence)
      (if init
          (setq init nil)
          (write-char #\  out))
      (princ (funcall key x) out))
    (terpri out)))

(declaim (ftype (function * (values fixnum &optional)) read-fixnum))
(defun read-fixnum (&optional (in *standard-input*))
  "NOTE: cannot read -2^62"
  (macrolet ((%read-byte ()
               `(the (unsigned-byte 8)
                     #+swank (char-code (read-char in nil #\Nul))
                     #-swank (sb-impl::ansi-stream-read-byte in nil #.(char-code #\Nul) nil))))
    (let* ((minus nil)
           (result (loop (let ((byte (%read-byte)))
                           (cond ((<= 48 byte 57)
                                  (return (- byte 48)))
                                 ((zerop byte) ; #\Nul
                                  (error "Read EOF or #\Nul."))
                                 ((= byte #.(char-code #\-))
                                  (setq minus t)))))))
      (declare ((integer 0 #.most-positive-fixnum) result))
      (loop
        (let* ((byte (%read-byte)))
          (if (<= 48 byte 57)
              (setq result (+ (- byte 48)
                              (* 10 (the (integer 0 #.(floor most-positive-fixnum 10))
                                         result))))
              (return (if minus (- result) result))))))))

(defmacro dbg (&rest forms)
  #+swank
  (if (= (length forms) 1)
      `(format *error-output* "~A => ~A~%" ',(car forms) ,(car forms))
      `(format *error-output* "~A => ~A~%" ',forms `(,,@forms)))
  #-swank (declare (ignore forms)))

(defmacro define-int-types (&rest bits)
  `(progn
     ,@(mapcar (lambda (b) `(deftype ,(intern (format nil "UINT~A" b)) () '(unsigned-byte ,b))) bits)
     ,@(mapcar (lambda (b) `(deftype ,(intern (format nil "INT~A" b)) () '(signed-byte ,b))) bits)))
(define-int-types 2 4 7 8 15 16 31 32 62 63 64)

(declaim (inline println))
(defun println (obj &optional (stream *standard-output*))
  (let ((*read-default-float-format* 'double-float))
    (prog1 (princ obj stream) (terpri stream))))

(defconstant +mod+ 1000000007)

;;;
;;; Body
;;;

(defun main ()
  (let* ((n (read))
         (graph (make-array n :element-type 'list :initial-element nil))
         (colors (make-array n :element-type 'bit)))
    (dotimes (i (- n 1))
      (let ((a (- (read-fixnum) 1))
            (b (- (read-fixnum) 1)))
        (push a (aref graph b))
        (push b (aref graph a))))
    (multiple-value-bind (quot rem) (floor n 3)
      (let* ((num1 (+ quot (if (>= rem 1) 1 0)))
             (num2 (+ quot (if (>= rem 2) 1 0)))
             (num3 quot)
             (nums1 (loop for i from 1 to num1 collect (- (* i 3) 2)))
             (nums2 (loop for i from 1 to num2 collect (- (* i 3) 1)))
             (nums3 (loop for i from 1 to num3 collect (* i 3))))
        (dbg num1 num2 num3)
        (labels ((dfs (v parent color)
                   (setf (aref colors v) color)
                   (dolist (child (aref graph v))
                     (unless (= child parent)
                       (dfs child v (logxor color 1))))))
          (dfs 0 -1 0)
          (let* ((vs0 (loop for v below n
                            when (zerop (aref colors v))
                            collect v))
                 (vs1 (loop for v below n
                            when (= 1 (aref colors v))
                            collect v))
                 (vs0-size (length vs0))
                 (vs1-size (length vs1))
                 (res (make-array n :element-type 'uint32)))
            (when (> vs0-size vs1-size)
              (rotatef vs0 vs1)
              (rotatef vs0-size vs1-size))
            (dbg vs0 vs1 vs0-size vs1-size)
            (dbg nums1 nums2 nums3)
            (if (<= vs0-size num3)
                (progn
                  (dolist (v0 vs0)
                    (if nums3
                        (setf (aref res v0) (pop nums3))
                        (error "Huh?")))
                  (dolist (v1 vs1)
                    (cond (nums3 (setf (aref res v1) (pop nums3)))
                          (nums2 (setf (aref res v1) (pop nums2)))
                          (nums1 (setf (aref res v1) (pop nums1)))
                          (t (error "Huh?")))))
                (progn
                  (dolist (v0 vs0)
                    (cond (nums2 (setf (aref res v0) (pop nums2)))
                          (nums3 (setf (aref res v0) (pop nums3)))
                          (t (error "Huh?"))))
                  (dolist (v1 vs1)
                    (cond (nums1 (setf (aref res v1) (pop nums1)))
                          (nums3 (setf (aref res v1) (pop nums3)))
                          (t (error "Huh?"))))))
            (println-sequence res)))))))

#-swank (main)

;;;
;;; Test and benchmark
;;;

#+swank
(defun io-equal (in-string out-string &key (function #'main) (test #'equal))
  "Passes IN-STRING to *STANDARD-INPUT*, executes FUNCTION, and returns true if
the string output to *STANDARD-OUTPUT* is equal to OUT-STRING."
  (labels ((ensure-last-lf (s)
             (if (eql (uiop:last-char s) #\Linefeed)
                 s
                 (uiop:strcat s uiop:+lf+))))
    (funcall test
             (ensure-last-lf out-string)
             (with-output-to-string (out)
               (let ((*standard-output* out))
                 (with-input-from-string (*standard-input* (ensure-last-lf in-string))
                   (funcall function)))))))

#+swank
(defun get-clipbrd ()
  (with-output-to-string (out)
    (run-program "powershell.exe" '("-Command" "Get-Clipboard") :output out :search t)))

#+swank (defparameter *this-pathname* (uiop:current-lisp-file-pathname))
#+swank (defparameter *dat-pathname* (uiop:merge-pathnames* "test.dat" *this-pathname*))

#+swank
(defun run (&optional thing (out *standard-output*))
  "THING := null | string | symbol | pathname

null: run #'MAIN using the text on clipboard as input.
string: run #'MAIN using the string as input.
symbol: alias of FIVEAM:RUN!.
pathname: run #'MAIN using the text file as input."
  (let ((*standard-output* out))
    (etypecase thing
      (null
       (with-input-from-string (*standard-input* (delete #\Return (get-clipbrd)))
         (main)))
      (string
       (with-input-from-string (*standard-input* (delete #\Return thing))
         (main)))
      (symbol (5am:run! thing))
      (pathname
       (with-open-file (*standard-input* thing)
         (main))))))

#+swank
(defun gen-dat ()
  (uiop:with-output-file (out *dat-pathname* :if-exists :supersede)
    (format out "")))

#+swank
(defun bench (&optional (out (make-broadcast-stream)))
  (time (run *dat-pathname* out)))

;; To run: (5am:run! :sample)
#+swank
(it.bese.fiveam:test :sample
  (it.bese.fiveam:is
   (common-lisp-user::io-equal "5
1 2
1 3
3 4
3 5
"
    "1 2 5 4 3
")))


Measured memory_bytes: 53176