#include <bits/stdc++.h>
using namespace std;

int main() {
    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());
    sort(B.begin(), B.end());

    int cnt = 0;
    double ans = 0;

    do {
        do {
            int a = 0, b = 0;
            for (int i = 0; i < N; i++) {
                if (A[i] > B[i])
                    a++;
                else
                    b++;
            }
            if (a > b)
                ans++;
            cnt++;
        } while (next_permutation(A.begin(), A.end()));
    } while (next_permutation(B.begin(), B.end()));

    cout << ans / cnt << endl;
}