import itertools

n = int(input())
a = list(map(int, input().split()))
b = list(map(int, input().split()))

game = 0
awin = 0
for i in itertools.permutations(a, n):
    for j in itertools.permutations(b, n):
        a_score = 0
        for k in range(n):
            if i[k] > j[k]:
                a_score += 1
            elif i[k] < j[k]:
                a_score -= 1
        game += 1
        if a_score > 0:
            awin += 1
print(awin / game)