from itertools import permutations

n = int(input())
A = list(map(int, input().split()))
B = list(map(int, input().split()))

ans = 0
fact = 1
for i in range(1, n + 1):
    fact *= i
for P1 in permutations(range(n)):
    for P2 in permutations(range(n)):
        C = [0, 0]
        for i in range(n):
            p1i, p2i = P1[i], P2[i]
            if A[p1i] > B[p2i]:
                C[0] += 1
            elif A[p1i] < B[p2i]:
                C[1] += 1
        if C[0] > C[1]:
            ans += 1
ans /= fact * fact
print(ans)