from random import shuffle
N = int(input())
A = list(map(int,input().split()))
B = list(map(int,input().split()))
s = 0
t = 0
for _ in range(100000):
    shuffle(A)
    shuffle(B)
    cnt = 0
    for i in range(N):
        if A[i] > B[i]:
            cnt += 1
        if A[i] < B[i]:
            cnt -= 1
    if cnt >= 1:
        s += 1
    t += 1
print(s / t)