def fun(a,b):
    a=int(a)
    b=int(b)
    return (a+b)/2

n = int(input())
y = []

a = input().split()
for i in range(len(a)):
    a[i] = int(a[i])
for i in range(n-1):
    a.sort()
    x = fun(a[0],a[1])
    del a[0]
    del a[0]

    a.append(x)
    
print(a[0])


