import itertools
N=int(raw_input())
A=map(int,raw_input().split())
B=map(int,raw_input().split())
A.sort()
tot=0
ans=0.0
for curA in itertools.permutations(A):
    awin=0
    bwin=0
    tot+=1
    #print curA
    for i in range(N):
        if curA[i]>B[i]:
            awin+=1
        if curA[i]<B[i]:
            bwin+=1
    #print awin,bwin
    if awin>bwin:
        ans+=1
print ans/tot