(defparameter *N* (read))
(defparameter *A* (make-array *N* :initial-element 0))

(defun median (a)
    (let ((L (length a)))
    (if (zerop(mod L 2))
        (/ (+ (aref a (/ L 2)) (aref a (1- (/ L 2)))) 2)
        (aref a (/ (1- L) 2)))))

(defun read-seqence (a n) (dotimes (i n) (setf (aref a i) (read))))

(defun main () (read-seqence *A* *N*) (sort *A* #'<) (format t "~A~%" (float (median *A*))))

(main)