; 中央値を求める
(defun main ()
  (let* ((n (read))
         (m (floor (1- n) 2))
         (xs (sort (loop repeat n collect (read)) #'<))
         (ans (if (evenp n)
                  (/ (+ (elt xs m) (elt xs (1+ m))) 2d0)
                  (elt xs m))))
    (format t "~f~%" ans)))
(main)