#define _USE_MATH_DEFINES
#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<string>
#include<iostream>
#include<iostream>
#include<cctype>
#include<cstdio>
#include<vector>
#include<stack>
#include<queue>
#include <algorithm>
#include<math.h>
#include<set>
#include<map>
#include <sstream>
#include<iomanip>
#include <ctype.h>
using namespace std;

//#include<bits/stdc++.h>


int main() {


	int n;
	cin >> n;
	int p[10] = {};
	for (int i = 0; i < n; i++)p[i] = i;
	int t = 0;
	int a[10] = {}, b[10] = {};
	for (int i = 0; i < n; i++)
	{
		
		cin >> a[i];
		
	}

	for (int i = 0; i < n; i++)
	{
		
		cin >> b[i];

	}
	int r=0;
	for (int i = 0; i < n; i++)p[i] = i;
	do {
		int v = 0;
		for (int i = 0; i < n; i++) {
			if (a[p[i]] > b[i])v++;
			else v--;
			//cout << a[p[i]];
		}
		
		if (v > 0)r++;
		t++;
	} while (next_permutation(p,p+n));
	cout << (double)r / (double)t << endl;;

	return 0;
}