#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include<iomanip>

using namespace std;

#define rep(i,n) for(int i=0;i<n;i++)
#define REP(i,a,n) for(int i=a;i<n;i++)

typedef long long ll;

template<class T>bool chmax(T &a, const T &b) { if (a<b) { a = b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a = b; return 1; } return 0; }

void Main()
{
    int N; cin >> N;
    int a[5];
    int b[5];
    rep(i,N) cin >> a[i];
    rep(i,N) cin >> b[i];
    sort(a, a + N);
    sort(b, b + N);
    int game_cnt = 0;
    int win_cnt = 0;
    do {
        do {
            int inner_a_win_cnt = 0;
            int inner_b_win_cnt = 0;
            rep(i,N) {
                if (a[i] > b[i]) ++inner_a_win_cnt;
                if (b[i] > a[i]) ++inner_b_win_cnt;
            }
            if (inner_a_win_cnt > inner_b_win_cnt) ++win_cnt;
            ++game_cnt;
        } while(next_permutation(b, b + N));
    } while(next_permutation(a, a + N));
    cout << ((double)win_cnt / (double)game_cnt) << endl;
}

int main()
{
	cin.tie(nullptr);
	ios_base::sync_with_stdio(false);
	cout << fixed << setprecision(15);
	Main();
}