import heapq
n = int(input())
v = list(map(int,input().split()))
heapq.heapify(v)
print(v)
for _ in range(n-1):
    x = heapq.heappop(v)
    y = heapq.heappop(v)
    heapq.heappush(v,(x+y)/2)
print(v[0])