#include <algorithm>
#include <array>
#include <cmath>
#include <deque>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>
using namespace std;

int score1 = 0, score2 = 0;
long long MOD = 1000000007;
vector<int> a;
vector<int> b;
vector<bool> check;


void dfs(int x, int s1, int s2) {
    if (x == (int)a.size()) {
        if (s1 > s2) score1++;
        else score2++;
    }
    for (int i = 0; i < (int)b.size(); i++) {
        if (check[i]) continue;
        check[i] = true;
        if (a[x] > b[i]) dfs(x+1, s1+1, s2);
        else dfs(x+1, s1, s2+1);
        check[i] = false;
    }
}


int main() {
    int n;
    cin >> n;
    a = vector<int>(n);
    b = vector<int>(n);
    for (int i = 0; i < n; i++) cin >> a[i];
    for (int i = 0; i < n; i++) cin >> b[i];
    check = vector<bool>(n, false);
    dfs(0, 0, 0);
    cout << (double)score1 / (score1+score2) << endl;
}