#include <bits/stdc++.h>
using namespace std;
using ll = int64_t;
using Vll =vector<ll>;
using VVll =vector<vector<ll>>;
template <class T>
using Vc = vector<T>;
template <class T>
using VVc = vector<vector<T>>;

void Z(ll i){ cout<<"Test"<<i<<endl; }



int main(){
    ll n,a,b;
    cin>>n;
    Vll A(n),B(n);

    for(ll i=0;i<n;i++){
        cin>>a;
        A.at(i)=a;

    }

    for(ll i=0;i<n;i++){
        cin>>a;
        B.at(i)=a;
        
    }




    ll aw=0,bw=0,nw=0;


    sort(A.begin(),A.end());
    sort(B.begin(),B.end());


    

    do{

        Vll B_=B;
        
        do{
            ll ap=0,bp=0;

            for(ll i=0;i<n;i++){
                if(A.at(i)>B_.at(i)) ap++;
                else bp++;

            }

            if(ap>bp) aw++;
            else if(ap<bp) bw++;
            else nw++;

        }while(next_permutation(B_.begin(),B_.end()));

    }while(next_permutation(A.begin(),A.end()));


    double ans;

    ans=(double)(aw)/(aw+bw+nw);

    cout<<ans<<endl;









}