#include <bits/stdc++.h>
#define int long long
#define YES cout<<"YES"<<endl;
#define NO cout<<"NO"<<endl;
#define Yes cout<<"Yes"<<endl;
#define No cout<<"No"<<endl;
using namespace std;
const int INF=1e9+7;

signed main(){
  int N;cin>>N;
  std::vector<int> a(N),b(N);
  for(int i=0;i<N;i++)cin>>a[i];
  for(int i=0;i<N;i++)cin>>b[i];
  sort(a.begin(),a.end());
  sort(b.begin(),b.end());
  double ans=0;double k=0;
  do{
    do{
      int A,B;A=B=0;k++;
      for(int i=0;i<N;i++){
        if(a[i]<b[i])B++;
        if(a[i]>b[i])A++;
      }
      //cout<<A<<" "<<B<<endl;
      if(A>B)ans++;
    }while(next_permutation(a.begin(),a.end()));
  }while(next_permutation(b.begin(),b.end()));
  cout<<ans/k<<endl;
}