N = int(input())
L = list(map(int, input().split()))

max = max(L)
min = min(L)
median = (max+min)/2

if N % 2 != 0:
    print(median)
else:
    closest_l = sorted([(n, abs(median-n)) for n in L], key=lambda tup: tup[1])
    print(sum([n for n, _ in closest_l[:2]])/2)