import numpy as np

N = input()
N = int(N)
stN = str(N)
p = input().split()
p_l = [int(s) for s in p]

p_sort = sorted(p_l,reverse=True)
print(p_sort)
for i in range(0,N-1):
    x = p_sort.pop()
    y = p_sort.pop()
    z = (x+y)/2
    p_sort.append(z)
    #print(p_sort)

print(p_sort[0])