import itertools

n = int(input())
A = list(map(int, input().split()))
B = list(map(int, input().split()))
a_rate_numerator = 0
count = 0

for a in itertools.permutations(A, n):
	for b in itertools.permutations(B, n):
		count += 1
		a_score = 0
		b_score = 0
		for i in range(n):
			if a[i] > b[i]:
				a_score += 1
			elif b[i] > a[i]:
				b_score += 1
		if a_score > b_score:
			a_rate_numerator += 1

print(a_rate_numerator / count)