
n=int(input())
ans=0
v=list(map(int,input().split()))
v.sort()

if n>2:
    for i in range(2,n):
        ans=(v[0]+v[1])*(2**(-n+1))+v[i]*(2**(-n+i))
else:
    ans=(v[0]+v[1])*(2**(-n+1))

if ans-int(ans)==0:
    print(int(ans))
else:
    print(ans)


