# -*- coding: utf-8 -*-
__author__ = 'yuuki'
#No.275 中央値を求めよ

N = input()
NL = map(int,raw_input().split())
NL.sort()

if len(NL) % 2 == 0:
    print (NL[len(NL)/2] + NL[len(NL)/2 - 1]) / 2.0
else:
    print NL[len(NL)/2]