N=int(input())
v=list(map(int,input().split()))
v.sort()
if len(v)==1:
    print(v[0])
elif len(v)==2:
    print((v[0]+v[1])/2)
else:
    s=(v[0]+v[1])/2
    for j in range(2,N):
        s+=(s+v[j])/2
    print(s)