from itertools import permutations

n = int(input())
A = list(map(int, input().split()))
B = list(map(int, input().split()))
As = list(permutations(A, n))
Bs = list(permutations(B, n))

print(As)
print(Bs)
vic = 0
for a in As:
    for b in Bs:
        if sum([1 for i, j in zip(a, b) if i > j]) > int(n//2):
            vic += 1
            
print(vic / (len(As)*len(Bs)))