#include <bits/stdc++.h>
#define err(args...) {}
#ifdef DEBUG
#include "_debug.cpp"
#endif
using namespace std;
using ll = long long;
int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    int n;
    cin >> n;
    vector<int> a(n), b(n);
    for(int i = 0; i < n; i++) {
        cin >> a[i];
    }
    for(int i = 0; i < n; i++) {
        cin >> b[i];
    }
    sort(a.begin(), a.end());
    int win = 0, games = 0;
    do {
        sort(b.begin(), b.end());
        do {
            int a_score = 0, b_score = 0;
            for(int i = 0; i < n; i++) {
                a_score += a[i] > b[i];
                b_score += b[i] > a[i];
            }
            win += a_score > b_score;
            games++;
        } while(next_permutation(b.begin(), b.end()));
    } while(next_permutation(a.begin(), a.end()));
    cout << double(win) / games << endl;
    return 0;
}