#include <algorithm>
#include <iostream>
#include <stack>
#include <queue>
#include <math.h>
#include <cmath>
#include <string>
#include <iterator>
#include <map>
#include <set>
#include <iomanip>
#include <vector>
#include <cstdint>
using namespace std;
using ll = long long;
using ld = long double;
using P = pair<ll, ll>;
using Graph = vector<vector<int>>;
int dx[] = {0, 1, 0, -1, 1, 1, -1, -1};
int dy[] = {1, 0, -1, 0, 1, -1, 1, -1};
#define rep(i, N) for(int i = 0; i < N; i++)
#define rep2(i, l, r) for (ll i = (ll)l; i < (ll)(r); i++)
#define INF 1000000000
#define MAX 200001
#define PI 3.141592653589793

#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
const ll MOD = 1000000007;

template <typename T > inline string toString(const T &a) {ostringstream oss; oss << a; return oss.str();};

int main(){
    int N;
    cin >> N;
    vector<int> A(N),B(N);
    rep(i,N) cin >> A[i];
    rep(i,N) cin >> B[i];
    sort(A.begin(),A.end());
    sort(B.begin(),B.end());
    double shiai = 0;
    double win = 0;
    do{
        do{
            int win_cnt = 0;
            int lose_cnt = 0;
            rep(i,N){
                if(A[i] > B[i]) win_cnt++;
                else lose_cnt++;
            }
            if(win_cnt > lose_cnt) win++;
            shiai++;
        }while(next_permutation(B.begin(),B.end()));
    }while(next_permutation(A.begin(),A.end()));
    cout << win / shiai << endl;
}