import sys
# sys.setrecursionlimit(1000010)
input=lambda:sys.stdin.readline().strip()
# write=lambda x:sys.stdout.write(str(x)+'\n')
I=lambda:input()
II=lambda:int(input())
LI=lambda:list(input())
MII=lambda:map(int,input().split())
LMII=lambda:list(map(int,input().split()))

# from bisect import bisect_left,bisect,insort
from collections import deque,Counter,namedtuple,defaultdict
# from copy import deepcopy
# from decimal import Decimal
# from datetime import datetime,timedelta
from functools import cmp_to_key,reduce,lru_cache
# from fractions import Fraction
from heapq import heapify,heappush,heappop
from itertools import permutations,combinations,accumulate
from math import inf,sqrt,isqrt,gcd,factorial,ceil,floor,e,log,log2,log10,pi,sin,cos,tan,asin,acos,atan,atan2
# from numba import jit
# from operator import or_,xor,add,mul
from random import randint,shuffle,getrandbits
# from sortedcontainers import SortedSet

def solve():
    n=II()
    a=LMII()
    b=LMII()
    win=0;cnt=0
    for p in permutations(a):
        for q in permutations(b):
            cnt+=1
            c=0
            for i in range(n):
                if p[i]>q[i]:
                    c+=1
            if c>n-c:
                win+=1
    print(win/cnt)
    return


test=1
# test=int(input())
for _ in range(test):
    solve()