n = int(input())
v = list(map(int, input().split()))
sort_v = sorted(v, reverse=False)
print(sort_v)
sum_tmp = 0
for i in range(2, n):
  sum_tmp += sort_v[i]*(2**(i-1))
sum_all = sort_v[0] + sort_v[1] + sum_tmp
div = 2 ** (n-1)
ans = sum_all / div
print(ans)
  
  