N = int(input())
v = [i for i in map(int,input().split())]
import heapq
heapq.heapify(v)

while len(v) >= 2:
  a = heapq.heappop(v)
  b = heapq.heappop(v)
  heapq.heappush(v,(a+b)/2)
  
print(heapq.heappop(v))