#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

#define rep(i, n) for (int i = 0; i < (n); i++)
#define all(x) (x).begin(), (x).end()

int n, win = 0, cnt = 0;
vector<int> A, B;

void fight()
{
    int mini_win = 0;
    cnt++;
    rep(i, n)
    {
        mini_win += A[i] > B[i] ? 1 : -1;
    }
    win += mini_win > 0 ? 1 : 0;
}

int main()
{
    cin >> n;
    A.resize(n);
    rep(i, n)
    {
        cin >> A[i];
    }
    B.resize(n);
    rep(i, n)
    {
        cin >> B[i];
    }

    sort(all(A));
    do
    {
        sort(all(B));
        do
        {
            fight();
        } while (next_permutation(all(B)));
    } while (next_permutation(all(A)));

    printf("%.2f\n", (float)win / cnt);
}