def main():

  import sys

  from collections import deque

  n=int(eval(input()))

  v=list(map(int,sys.stdin.read().split()))

  w=deque(sorted(v))

  ans=(w.popleft()+w.popleft())/2

  for i in range(n-2):

    ans=ans/2

    ans+=w.popleft()/2

  print(ans)

if __name__=="__main__":

  main()
def main():

  n=int(eval(input()))

  w=sorted(map(int,input().split()))

  ans=(w[0]+w[1])/2

  for i in range(2,n):

    ans=ans/2+w[i]/2

  print(ans)

if __name__=="__main__":

  main()
def main():
    import sys
    from collections import deque

    n = int(eval(input()))
    v = list(map(int, sys.stdin.read().split()))
    w = deque(sorted(v))
    ans = (w.popleft() + w.popleft()) / 2
    for i in range(n - 2):
        ans = ans / 2
        ans += w.popleft() / 2
    print(ans)


if __name__ == "__main__":
    main()

def main():
    n = int(eval(input()))
    w = sorted(map(int, input().split()))
    ans = (w[0] + w[1]) / 2
    for i in range(2, n):
        ans = ans / 2 + w[i] / 2
    print(ans)


if __name__ == "__main__":
    main()

-    import sys -    from collections import deque - -    v = list(map(int, sys.stdin.read().split())) -    w = deque(sorted(v)) -    ans = (w.popleft() + w.popleft()) / 2 -    for i in range(n - 2): -        ans = ans / 2 -        ans += w.popleft() / 2 +    w = sorted(map(int, input().split())) +    ans = (w[0] + w[1]) / 2 +    for i in range(2, n): +        ans = ans / 2 + w[i] / 2