from itertools import groupby, accumulate, product, permutations, combinations
from statistics import mean
N = int(input())
A = list(map(int, input().split()))
B = list(map(int, input().split()))

ans = []
for p in permutations(A,N):
    for q in permutations(B,N):
        cnt = 0
        for i in range(N):
            if p[i]>q[i]:
                cnt += 1
        if cnt>N//2:
            ans.append(1)
        else:
            ans.append(0)
ans = mean(ans)
print(ans)