Problem:
Score : 300 points

Problem Statement

There is a rectangle in a coordinate plane. The coordinates of the four vertices are (0,0), (W,0), (W,H), and (0,H).
You are given a point (x,y) which is within the rectangle or on its border. We will draw a straight line passing through (x,y) to cut the rectangle into two parts. Find the maximum possible area of the part whose area is not larger than that of the other. Additionally, determine if there are multiple ways to cut the rectangle and achieve that maximum.

Constraints

1 \leq W,H \leq 10^9

0\leq x\leq W

0\leq y\leq H

All values in input are integers.

Input

Input is given from Standard Input in the following format:

W H x y

Output

Print the maximum possible area of the part whose area is not larger than that of the other, followed by 1 if there are multiple ways to cut the rectangle and achieve that maximum, and 0 otherwise.

The area printed will be judged correct when its absolute or relative error is at most 10^{-9}.

Sample Input 1

2 3 1 2

Sample Output 1

3.000000 0

The line x=1 gives the optimal cut, and no other line does.

Sample Input 2

2 2 1 1

Sample Output 2

2.000000 1

Solution in Common Lisp (SBCL 2.0.3) (judge verdict: Wrong Answer)

;;; Utils (quoted from https://competitive12.blogspot.com/2020/03/common-lisp.html)


;; Read fixnum

(declaim (ftype (function * (values fixnum &optional)) read-fixnum))
(defun read-fixnum (&optional (in *standard-input*))
  (declare (inline read-byte)
           #-swank (sb-kernel:ansi-stream in))
  (macrolet ((%read-byte ()
               `(the (unsigned-byte 8)
                     #+swank (char-code (read-char in nil #\Nul))
                     #-swank (read-byte in nil 0))))
    (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) (the (integer 0 #.(floor most-positive-fixnum 10)) (* result 10))))
              (return (if minus (- result) result))))))))

;; fast read-line

(defmacro buffered-read-line (&optional (buffer-size 30) (in '*standard-input*) (term-char #\Space))
  (let ((buffer (gensym))
        (character (gensym))
        (idx (gensym)))
    `(let* ((,buffer (load-time-value (make-string ,buffer-size :element-type 'base-char))))
       (declare (simple-base-string ,buffer)
                (inline read-byte))
       (loop for ,character of-type base-char =
             ,(if (member :swank *features*)
                  `(read-char ,in nil #\Newline) ; on SLIME
                `(code-char (read-byte ,in nil #.(char-code #\Newline))))
             for ,idx from 0
             until (char= ,character #\Newline)
             do (setf (schar ,buffer ,idx) ,character)
             finally (when (< ,idx ,buffer-size)
                       (setf (schar ,buffer ,idx) ,term-char))
             (return (values ,buffer ,idx))))))


;;; invoke child process

#-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))))



;-------------------
; Write code here
;-------------------



(defun solve (w h x y)
  (if (and (= (* x 2) w)
          (= (* y 2) h))
      (cons (coerce (/ (* w h) 2) 'double-float) 0)
      (cons (coerce (/ (* w h) 2) 'double-float) 1)))

(defun main ()
   (let ((l (read-from-string (concatenate 'string "(" (read-line) ")"))))
     (destructuring-bind (w h x y) l
       (setq ans (solve w h x y))
       (let ((*read-default-float-format* 'double-float))
         (format t "~a ~a" (first ans) (rest ans)))
       (fresh-line))))

(main)