/**
	author:  shobonvip
	created: 2025.05.21 07:13:48
**/

#include<bits/stdc++.h>
using namespace std;

//* ATCODER
#include<atcoder/all>
using namespace atcoder;
typedef modint mint;
//*/

/* BOOST MULTIPRECISION
#include<boost/multiprecision/cpp_int.hpp>
using namespace boost::multiprecision;
//*/

typedef long long ll;

#define rep(i, s, n) for (int i = (int)(s); i < (int)(n); i++)
#define rrep(i, s, n) for (int i = (int)(n)-1; i >= (int)(s); i--)
#define all(v) v.begin(), v.end()

template <typename T> bool chmin(T &a, const T &b) {
	if (a <= b) return false;
	a = b;
	return true;
}

template <typename T> bool chmax(T &a, const T &b) {
	if (a >= b) return false;
	a = b;
	return true;
}

template <typename T> T max(vector<T> &a){
	assert(!a.empty());
	T ret = a[0];
	for (int i=0; i<(int)a.size(); i++) chmax(ret, a[i]);
	return ret;
}

template <typename T> T min(vector<T> &a){
	assert(!a.empty());
	T ret = a[0];
	for (int i=0; i<(int)a.size(); i++) chmin(ret, a[i]);
	return ret;
}

template <typename T> T sum(vector<T> &a){
	T ret = 0;
	for (int i=0; i<(int)a.size(); i++) ret += a[i];
	return ret;
}

void solve() {
	int n; cin >> n;
	vector<int> a(n), b(n);
	rep(i,0,n) cin >> a[i];
	rep(i,0,n) cin >> b[i];

	vector<int> p(n);
	iota(all(p), 0);

	double ans = 0;
	int all_match = 0;
	do {
		int wins = 0;
		int loses = 0;
		all_match++;
		rep(i,0,n) {
			if (a[i] > b[p[i]]) {
				wins += 1;
			}
			if (a[i] < b[p[i]]) {
				loses += 1;
			}
		}
		if (wins > loses) {
			ans += 1;
		}

	} while (next_permutation(all(p)));

	ans /= double(all_match);
	cout << fixed << setprecision(15);
	cout << ans << endl;
}

int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	
	solve();
}