#!/usr/bin/env python3
# -*- coding: utf-8 -*-

import random
import statistics

EXP_TIMES = 50000


def judge(pair):
    if pair[0] > pair[1]:
        return 1
    else:
        return 0


def conduct_experiment(n, acs, bcs):
    random.shuffle(acs)
    random.shuffle(bcs)
    w = sum(map(judge, zip(acs, bcs)))
    if w > n - w:
        return 1.0
    else:
        return 0.0


def main(times=EXP_TIMES):
    n = int(input())
    acs = list(map(int, input().split()))
    bcs = list(map(int, input().split()))
    ans = statistics.mean(conduct_experiment(n, acs, bcs)
                          for x in range(times))
    print("{ans:.5f}".format(ans=ans))

if __name__ == "__main__":
    main()