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

typedef long long ll;
typedef unsigned long long ull;

int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cout.precision(12);
    cout.setf(ios_base::fixed, ios_base::floatfield);
    
    int n;
    int a[4], b[4];
    cin >> n;
    for(int i=0;i<n;i++) cin >> a[i];
    for(int i=0;i<n;i++) cin >> b[i];
    
    int game = 0, win = 0;

    int pa[4], pb[4];
    iota(pa, pa+4, 0);
    do{
        iota(pb, pb+4, 0);
        do{
            int aw = 0, bw = 0;
            for(int i=0;i<n;i++){
                if(a[pa[i]] > b[pb[i]]) aw++;
                if(a[pa[i]] < b[pb[i]]) bw++;
            }
            game++;
            if(aw > bw) win++;
        }while(next_permutation(pb, pb+n));
    }while(next_permutation(pa, pa+n));
    
    cout << (win+0.0)/game << endl;

    return 0;
}