from itertools import permutations
import sys
input = sys.stdin.readline

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

    a_win, total = 0, 0
    for a in permutations(A):
        for b in permutations(B):
            a_, b_ = 0, 0
            for i in range(N):
                if a[i] > b[i]:
                    a_ += 1
                elif a[i] < b[i]:
                    b_ += 1
            if a_ > b_:
                a_win += 1
            total += 1
    print(a_win/total)

if __name__ == "__main__":
    main()