n = int(input())
v  = list(map(int, input().split()))
#h, w = list(map(int, input().split()))
v.sort()
ans = 0
point = (v[0]+v[1])/2
if n == 2:
    print(point)
else:
    for i in range(2, n):
        point = (point+v[i])/2

print(point)
