#include <bits/stdc++.h>
using namespace std;
#define int long long
#define rep(i,n) for(int i=0; i<(int)n; i++)
#define rep1(i,n) for(int i=1; i<(int)n; i++)
#define repa(i,a,n) for(int i=(a); i<(int)(n); i++)
#define all(vec) vec.begin(),vec.end()
#define COUT(x) cout<<(x)<<endl
#define YES(x) cout<<(x?"YES":"NO")<<endl
#define Yes(x) cout<<(x?"Yes":"No")<<endl
using vi = vector<int>;
using vs = vector<string>;
using vvi = vector<vi>;
using pii = pair<int, int>;
using psi = pair<string, int>;
const int dx[4] = {1, 0,-1, 0};
const int dy[4] = {0, 1, 0,-1};
const int mod = 1e9+7;
int gcd(int a, int b){if(a%b == 0){return(b);}else{return(gcd(b, a%b));}}
int lcm(int a, int b){return a/gcd(a, b)*b;}
//cout << fixed << setprecision(15);
int N, M, K, H, W, L, R, X, Y;
string S, T;
int INF = 1e18;

signed main(){
    cin >> N;
    vi A(N); rep(i,N) cin >> A[i];
    vi B(N); rep(i,N) cin >> B[i];
    sort(all(A));
    int aw = 0;
    int bw = 0;
    int drow = 0;

    do{
        sort(all(B));
        do{
            int ca = 0;
            int cb = 0;
            rep(i,N){
                if(A[i]>B[i]) ca++;
                else if(A[i]<B[i]) cb++;
            }
            if (ca>cb)aw++;
            else if(ca==cb) drow++;
            else bw++;
        }while(next_permutation(all(B)));
    }while(next_permutation(all(A)));

    cout << fixed << setprecision(4);
    bw += aw+drow;
    COUT((double)aw/(double)bw);
    return 0;
}