#include<cstdio>
#include<cstdlib>
#include<algorithm>
#include<iostream>
#include<queue>
#include<vector>
#include <bitset>
#include<math.h>
using namespace std;
#define INF 10000000
#define MOD 1000000007
typedef long long ll;
typedef pair<int,int> P;

int C[10][10],perm1[4]={0,1,2,3},perm2[4]={0,1,2,3};

int main(){
  int N,countA=0,countB=0,A[4],B[4],tempA=0,tempB=0,ans=0;
  cin>>N;
  for(int i=0;i<N;i++) cin>>A[i];

  for(int i=0;i<N;i++) cin>>B[i];
  
  do{
    do{
      tempA=tempB=0;
      for(int i=0;i<N;i++){
        if(A[perm1[i]]>B[perm2[i]]) tempA++;
        else if(A[perm1[i]]<B[perm2[i]]) tempB++;
      }
      if(tempA>tempB) countA++;
      else if(tempA<tempB) countB++;
      else ans++;
    }while(next_permutation(perm2,perm2+N));
  }while(next_permutation(perm1,perm1+N));

  cout<<(double)countA/(countA+countB+ans)<<endl;
}