N = int(input())
vi = list(map(int,input().split()))
vi_sort = sorted(vi)

print(vi_sort)

if N == 2:
  print((vi[0]+vi[1])/2)
else:
  i = 0
  while i < (N-1):
    new_number = (vi_sort[0]+vi_sort[1])/2
    del vi_sort[0:2]
    vi_sort.append(new_number)
    vi_sort.sort()
    i += 1
    
  print(vi_sort[0])