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

from heapq import *
que = []
heapify(que)

for v in v_list:
    heappush(que, -v)

while len(que) != 1:
    a = que.pop()
    b = que.pop()
    heappush(que, (a+b)/2)
print(abs(que.pop()))
