import itertools
N = int(input())
A = list(map(int,input().split()))
B = list(map(int,input().split()))    
a = list(itertools.permutations(A))
b = list(itertools.permutations(B))
win_A = 0
win_B = 0
sum = 0
for s in a:
    for t in b:
        win_a = 0
        win_b = 0
        sum += 1
        for i in range(N):
            if(s[i]>t[i]):
                win_a += 1
            elif(s[i]<t[i]):
                win_b += 1
        if(win_a>win_b):
            win_A += 1
        if(win_a<win_b):
            win_B += 1
print(win_A/sum)