from collections import deque
N = int(input())
v = list(map(int, input().split()))
v.sort()
ans = deque()

while len(v) > 1:
    odd = []
    if len(v) % 2 == 1:
        odd.append(v[len(v) - 1])

    for i in range(1, len(v), 2):
        ans.append((v[i - 1] + v[i]) / 2)

    if len(odd) == 1:
        ans.append(odd[0])
    v = ans
    ans = deque()

print(v[0])