N=int(input())
A=input().split(" ")
A=[int(i) for i in A]
A.sort()

def act(A):
  if len(A)%2==0:
    A_=[]
    for i in range(int(len(A)/2)):
      A_.append((A[2*i]+A[2*i+1])/2)
    return A_
  
  elif len(A)%2==1:
    A_=[]
    for i in range(int((len(A)-1)/2)):
      A_.append((A[2*i]+A[2*i+1])/2)
    A_.append(A[len(A)-1])
    return A_
    
    
while len(A)>1:
  A=act(A)

print(A[0])