import itertools

n = int(input())
a = list(input().split())
b = list(input().split())
game = 0
wina = 0
for i in itertools.permutations(a, n):
    for j in itertools.permutations(b, n):
        for k in range(n):
            win = 0
            lose = 0
            if i[k] > j[k]:
                win += 1
            elif i[k] < j[k]:
                lose += 1
        game += 1
        if win > lose:
            wina += 1

print(wina / game)