#include <sstream>
#include <string>
#include <vector>
#include <map>
#include <algorithm>
#include <iostream>
#include <utility>
#include <set>
#include <cctype>
#include <queue>
#include <stack>
#include <cstdio>
#include <cstdlib>
#include <cmath>

#define INF 1000000000

using namespace std;
typedef long long ll;

const int MAXN = 5;
int A[MAXN], B[MAXN];
int N;
double ans = 0;
int cnt = 0;

int main(void) {
    cin >> 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);
    do {
        do {
            int win = 0, lose = 0;
            for (int i = 0; i < N; i++) {
                if (A[i] > B[i]) win++;
                else lose++;
            }
            if (win > lose) ans += 1;
            cnt++;
        } while (next_permutation(B, B+N));
    } while (next_permutation(A, A+N));
    cout << ans / cnt << endl;
    return 0;
}