(in-package :cl-user)
(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
           #\# #\> (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)

(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)

(defconstant +mod+ 1000000007)

(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)))

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

;; BEGIN_INSERTED_CONTENTS
(defpackage :cp/read-fixnum
  (:use :cl)
  (:export #:read-fixnum))
(in-package :cp/read-fixnum)

(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))))))))

;;;
;;; Queue with singly linked list
;;;

(defpackage :cp/queue
  (:use :cl)
  (:export #:queue #:make-queue #:enqueue #:dequeue #:queue-empty-p #:queue-peek #:enqueue-front))
(in-package :cp/queue)

(defstruct (queue (:constructor make-queue
                      (&optional list &aux (tail (last list))))
                  (:copier nil)
                  (:predicate nil))
  (list nil :type list)
  (tail nil :type list))

(declaim (inline enqueue))
(defun enqueue (obj queue)
  "Pushes OBJ to the end of QUEUE."
  (symbol-macrolet ((list (queue-list queue))
                    (tail (queue-tail queue)))
    (if (null list)
        (setf tail (list obj)
              list tail)
        (setf (cdr tail) (list obj)
              tail (cdr tail))))
  queue)

(declaim (inline dequeue))
(defun dequeue (queue)
  "Removes and returns the element at the front of QUEUE. Returns NIL if QUEUE
is empty."
  (pop (queue-list queue)))

(declaim (inline queue-empty-p))
(defun queue-empty-p (queue)
  (null (queue-list queue)))

(declaim (inline queue-peek))
(defun queue-peek (queue)
  (car (queue-list queue)))

(declaim (inline enqueue-front))
(defun enqueue-front (obj queue)
  "Pushes OBJ to the front of QUEUE."
  (symbol-macrolet ((list (queue-list queue))
                    (tail (queue-tail queue)))
    (if (null list)
        (setf tail (list obj)
              list tail)
        (push obj list))
    queue))

;; BEGIN_USE_PACKAGE
(eval-when (:compile-toplevel :load-toplevel :execute)
  (use-package :cp/queue :cl-user))
(eval-when (:compile-toplevel :load-toplevel :execute)
  (use-package :cp/read-fixnum :cl-user))
(in-package :cl-user)

;;;
;;; Body
;;;

(defconstant +inf+ #x7fffffff)
(declaim (ftype (function * (values (simple-array uint31 (*)) &optional)) make-dists))
(defun make-dists (start graph)
  (declare ((simple-array list (*)) graph))
  (let* ((n (ash (length graph) -1))
         (dists (make-array (* n 2) :element-type 'uint31 :initial-element +inf+))
         (que (make-queue)))
    (setf (aref dists start) 0)
    (enqueue start que)
    (loop until (queue-empty-p que)
          for v = (dequeue que)
          do (dolist (next (aref graph v))
               (when (= +inf+ (aref dists next))
                 (setf (aref dists next) (+ (aref dists v) 1))
                 (enqueue next que))))
    dists))

(defun main ()
  (let* ((n (read))
         (m (read))
         (p (read))
         (s (- (read) 1))
         (g (- (read) 1))
         (graph (make-array (* 2 n) :element-type 'list :initial-element nil)))
    (declare (uint31 n m p s g))
    (dotimes (i m)
      (let ((u (- (read-fixnum) 1))
            (v (- (read-fixnum) 1)))
        (push u (aref graph (+ n v)))
        (push (+ n v) (aref graph u))
        (push v (aref graph (+ n u)))
        (push (+ n u) (aref graph v))))
    (let ((dists-s (make-dists s graph))
          (dists-g (make-dists g graph))
          res)
      #>dists-s
      #>dists-g
      (dotimes (v n)
        (let ((slen-even (aref dists-s v))
              (slen-odd (aref dists-s (+ v n)))
              (glen-even (aref dists-g v))
              (glen-odd (aref dists-g (+ v n))))
          (if (evenp p)
              (when (or (<= (+ slen-even glen-even) p)
                        (<= (+ slen-odd glen-odd) p))
                (push (+ v 1) res))
              (when (or (<= (+ slen-even glen-odd) p)
                        (<= (+ slen-odd glen-even) p))
                (push (+ v 1) res)))))
      (if res
          (write-string
           (with-output-to-string (*standard-output* nil :element-type 'base-char)
             (println (length res))
             (map () #'println (nreverse res))))
          (println -1)))))

#-swank (main)

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

#+swank
(defun get-clipbrd ()
  (with-output-to-string (out)
    #+os-windows (run-program "powershell.exe" '("-Command" "Get-Clipboard") :output out :search t)
    #+os-unix (run-program "xsel" '("-b" "-o") :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* (or out (make-string-output-stream)))
         (res (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))))))
    (if out res (get-output-stream-string *standard-output*))))

#+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
   (equal "4
1
2
3
4
"
          (run "6 5 3
1 4
1 2
1 3
1 4
2 5
3 6
" nil)))
  (it.bese.fiveam:is
   (equal "-1
"
          (run "4 3 4
1 4
1 2
2 3
3 4
" nil)))
  (it.bese.fiveam:is
   (equal "6
1
2
4
7
9
10
"
          (run "10 9 5
1 10
7 2
4 9
5 3
1 9
2 9
8 7
8 5
6 4
10 2
" nil))))