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

using namespace std;

int main(){
    int n; cin >> n;
    vector<int> as(n), bs(n);
    for(int i=0; i<n; ++i) cin >> as[i];
    for(int i=0; i<n; ++i) cin >> bs[i];
    int num_play=0, win=0;
    sort(as.begin(), as.end());
    do{
        sort(bs.begin(), bs.end());
        do{
            int t=0;
            for(int i=0; i<n; ++i){
                t+=as[i]>bs[i];
            }
            ++num_play;
            win+=t>(n-t);
        }while(next_permutation(bs.begin(), bs.end()));
    }while(next_permutation(as.begin(), as.end()));
    cout << (double)win/num_play << endl;
    return 0;
}