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

int main() {
    int n;
    cin >> n;
    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, A + n);
    sort(B, B + n);

    int shiaisuu = 0;
    int teli = 0;

    do {
        do {
            shiaisuu++;

            int WinA = 0;
            int WinB = 0;
            for (int i = 0; i < n; i++) {
                if (A[i] > B[i]) WinA++;
                if (B[i] > A[i]) WinB++;
            }

            if (WinA > WinB) teli++;
        } while (next_permutation(B, B + n));
    } while (next_permutation(A, A + n));

    double kakuritu = (double)teli / (double)shiaisuu;

    cout << fixed << kakuritu << endl;
}