(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
;;;
;;; 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))

(defpackage :cp/read-schar
  (:use :cl)
  (:export #:read-schar))
(in-package :cp/read-schar)

(declaim (inline read-schar))
(defun read-schar (&optional (stream *standard-input*))
  (declare #-swank (sb-kernel:ansi-stream stream)
           (inline read-byte))
  #+swank (read-char stream nil #\Newline) ; on SLIME
  #-swank (code-char (read-byte stream nil #.(char-code #\Newline))))

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

;;;
;;; Body
;;;

(defconstant +inf+ #x7fffffff)
(defun main ()
  (declare #.opt
           (inline sort sb-impl::stable-sort-list))
  (let* ((h (read))
         (w (read))
         (ch (- (read) 1))
         (cw (- (read) 1))
         (dh (- (read) 1))
         (dw (- (read) 1))
         (plan (make-array (list h w) :element-type 'bit :initial-element 0))
         (dists (make-array (list h w) :element-type 'uint31 :initial-element +inf+))
         (que (make-queue)))
    (declare (uint16 h w ch cw dh dw))
    (dotimes (i h)
      (dotimes (j w (read-schar))
        (ecase (read-schar)
          (#\.)
          (#\# (setf (aref plan i j) 1)))))
    (setf (aref dists ch cw) 0)
    (enqueue (list* ch cw 0) que)
    (loop until (queue-empty-p que)
          for (i1 j1 . dist) of-type (uint31 uint31 . uint31) = (dequeue que)
          when (= dist (aref dists i1 j1))
          do (labels ((calc-cost (i2 j2)
                        (cond ((= 1 (aref plan i2 j2)) +inf+)
                              ((= 1 (+ (abs (- i1 i2)) (abs (- j1 j2)))) 0)
                              (t 1)))
                      (visit (i2 j2)
                        (when (and (<= 0 i2 (- h 1))
                                   (<= 0 j2 (- w 1)))
                          (let ((new-dist (+ dist (calc-cost i2 j2))))
                            (when (< new-dist (aref dists i2 j2))
                              (setf (aref dists i2 j2) new-dist)
                              (if (= dist new-dist)
                                  (enqueue-front (list* i2 j2 new-dist) que)
                                  (enqueue (list* i2 j2 new-dist) que)))))))
               (loop for i2 from (- i1 2) to (+ i1 2)
                     do (loop for j2 from (- j1 2) to (+ j1 2)
                              do (visit i2 j2)))))
    (println (if (= (aref dists dh dw) +inf+)
                 -1
                 (aref dists dh dw)))))

#-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 "1
"
          (run "4 4
1 1
4 4
..#.
..#.
.#..
.#..
" nil)))
  (it.bese.fiveam:is
   (equal "-1
"
          (run "4 4
1 4
4 1
.##.
####
####
.##.
" nil)))
  (it.bese.fiveam:is
   (equal "0
"
          (run "4 4
2 2
3 3
....
....
....
....
" nil)))
  (it.bese.fiveam:is
   (equal "2
"
          (run "4 5
1 2
2 5
#.###
####.
#..##
#..##
" nil))))


Measured memory_bytes: 67904