#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 main() {
    int n, score1, score2, ans1 = 0, ans2 = 0;
    cin >> n;
    vector<int> a(n);
    vector<int> b(n);
    for (int i = 0; i < n; i++) cin >> a[i];
    for (int i = 0; i < n; i++) cin >> b[i];
    vector<int> ind(n);
    iota(ind.begin(), ind.end(), 0);
    do {
        score1 = 0;
        score2 = 0;
        for (int i = 0; i < n; i++) {
            if (a[i] > b[ind[i]]) score1++;
            else if (a[i] < b[ind[i]]) score2++;
        }
        if (score1 > score2) ans1++;
        else ans2++;
    } while (next_permutation(ind.begin(), ind.end()));
    cout << (double)ans1 / (ans1+ans2) << endl;
}