N = int(input())
Vs = input().split()

if N == 2:
    print(sum([int(x) for x in Vs])/N)
else:
    lists = [int(x) for x in Vs]
    while N > 1:
        lists.sort()
        x = int((lists.pop(0) + lists.pop(0)) / 2)
        lists.insert(0, x)
        N -= 1

    print(lists[0])
