#include <algorithm>
#include <iostream>
#include <vector>

using namespace std;

int main() {
    int n;
    cin >> n;
    
    vector<vector<int>> v = vector<vector<int>>(2, vector<int>(n, 0));
    for (int i = 0; i < 2; ++i) {
        for (int j = 0; j < n; ++j) {
            int num;
            cin >> num;
            v[i][j] = num;
        }
    }
    
    sort(v[0].begin(), v[0].end());
    sort(v[1].begin(), v[1].end());
    
    int win = 0;
    int sum = 0;
    
    do {
        do {
            int win_a = 0;
            int win_b = 0;
            
            for (int i = 0; i < n; ++i) {
                if (v[0][i] > v[1][i]) {
                    win_a++;
                }
                if (v[0][i] < v[1][i]) {
                    win_b++;
                }
            }
            
            if (win_a > win_b) {
                win++;
            }
            
            sum++;
            
        } while (next_permutation(v[1].begin(), v[1].end()));
    } while (next_permutation(v[0].begin(), v[0].end()));

    cout << static_cast<double>(win) / sum << "\n";
    
    return 0;
}