(defvar N)
(defvar A)
(setq N (read-line))
(setq A (read-line))
(setq A (read-from-string (concatenate 'string "(" A ")")))
(setq A (sort A #'<))
(defvar L)
(setq L (length A))

(if (oddp L) (format 't "~d~%" (nth (/ (- L 1) 2) A))
  (format 't "~f~%" (/ (+ (nth (- (/ L 2) 1) A) (nth (/ L 2) A ) ) 2)))