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

n_list.sort()

new_list = []
ctr = 0

while len(n_list) > 1:
  n_list[ctr] = (n_list[ctr] + n_list[ctr+1])/2
  n_list.pop(ctr + 1)
  n_list.sort
  
print(n_list)