from itertools import permutations


n=int(input())
A=list(map(int,input().split()))
B=list(map(int,input().split()))
l1=list(permutations(range(n)))
l2=list(permutations(range(n)))
cnt=0
for x in l1:
    a,b=0,0
    for y in l2:
        for i in range(len(y)):
            if A[x[i]]>B[y[i]]:
                a+=1
            elif A[x[i]]<B[y[i]]:
                b+=1
            print(A[x[i]],B[y[i]])
    if a>b:
        cnt+=1
print(cnt/(n*n))