import itertools

N = int(input())
A = input().split()
B = input().split()
cnt = 0
all = 0

for i in itertools.permutations(A):
    for j in itertools.permutations(B):
        a_win = 0
        a_lose = 0
        for k in range(N):
            #print(k,i[k],j[k])
            if int(i[k]) > int(j[k]):
                a_win += 1
            if int(i[k]) < int(j[k]):
                a_lose += 1
        else:
            all += 1
            if a_win > a_lose:
                cnt += 1

print(cnt/all)