#include <iostream>
#include <vector>
#include <algorithm>
#include <map>
#include <queue>
#include <cstdio>
#include <ctime>
#include <assert.h>
#include <chrono>
#include <random>
#include <numeric>
#include <set>
using namespace std;
typedef long long int ll;
typedef unsigned long long ull;


int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    int n; cin >> n;
    vector<int> a(n),b(n);
    for(int i=0;i<n;i++){
        cin >> a[i];
    }
    for(int i=0;i<n;i++){
        cin >> b[i];
    }
    sort(a.begin(), a.end());
    sort(b.begin(), b.end());
    int al=0;
    int win=0;
    do{
        do{
            al++;
            int w=0;
            int l=0;
            for(int i=0;i<n;i++){
                if(a[i]>b[i])w++;
                else l++;
            }
            if(w>l)win++;
        }while(next_permutation(b.begin(), b.end()));
    }while(next_permutation(a.begin(), a.end()));
    printf("%.9f\n",(double)(win)/al );
}