#include <cstdlib>
#include <algorithm>
#include <iostream>
#include <cstdint>
#include <vector>
#include <string>
#include <complex>
#include <bitset>
#include <queue>
#include <stack>
#include <utility>
#include <unordered_set>
#include <unordered_map>

using namespace std;

static inline bool isOdd(int v)
{
    return v & 0x01;
}

int main()
{
    int N;
    cin >> N;

    std::vector<int> A;
    std::vector<int> B;
    for (size_t i = 0; i < N; ++i) {
        int v;
        cin >> v;
        A.push_back(v);
    }
    for (size_t i = 0; i < N; ++i) {
        int v;
        cin >> v;
        B.push_back(v);
    }

    size_t win = 0;
    size_t not_win = 0;

    std::sort(B.begin(), B.end());
    std::sort(A.begin(), A.end());
    do {
        size_t w = 0;
        size_t nw = 0;
        for (size_t i = 0; i < N; ++i) {
            if (A[i] > B[i]) {
                w++;
            }
            else {
                nw++;
            }
        }
        if (w > nw) {
            win++;
        }
        else {
            not_win++;
        }
    } while (std::next_permutation(B.begin(), B.end()));

    cout << (double)win / (win+not_win) << endl;

    return 0;
}