# coding: utf-8

ct = int(input().strip())
num = [int(x) for x in input().strip().split()]

num.sort()
last_key = len(num) - 1

if len(num) % 2 == 1:
    med_key = int(last_key / 2)
    print(num[med_key])
else:
    med_key_before = last_key // 2
    med_key_after = med_key_before + 1
    
    ans = (num[med_key_before] + num[med_key_after]) / 2
    print(ans)