(use srfi-1)
(define n (read))
(define (readn n)  (if (= n 0) '() (cons (read) (readn (- n 1)) ) ))
(define x (readn n))
(if (even? (length x)) (print(exact->inexact(/ (+  (list-ref x (-(quotient (length x) 2)1) ) (list-ref x (quotient (length x)2) ))2))) (print (list-ref x (+ (quotient (length x)2)1))))