n = int(input())
v = list(map(int,input().split()))
i = len(v)-1

for i in range(n-1):
    v.sort()
    new_num = (v[0] + v[len(v)-1]) / 2
    v[0] = new_num
    if i != n - 1:
        v.remove(v[len(v)-1])

print(new_num)

'''
    for j in range((n-1)-i):
        if j == 0:
            v[j] = new_num
        else:
            v.remove(v[len(v)-1])

'''
