from time import time
from random import shuffle

N=int(input())
A=list(map(int,input().split()))
B=list(map(int,input().split()))

START=time()
TIME_LIMIT=4

battle=win=0
while time()-START<=TIME_LIMIT:
    battle+=1
    shuffle(A)
    shuffle(B)

    k=0
    for i in range(N):
        k+=(A[i]>B[i])

    win+=(2*k>N)

print(win/battle)