import itertools

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

count = 0
all = 0
for i in itertools.permutations(A):
    for j in itertools.permutations(B):
        a_win, b_win = 0, 0
        all += 1
        for k in range(N):
            if i[k] > j[k]:
                a_win += 1
            elif j[k] > i[k]:
                b_win += 1
        if a_win > b_win:
            count += 1

ans = count/all
print(ans)