#define _USE_MATH_DEFINES

#include <iostream>
#include <iomanip>

#include <algorithm>
#include <cmath>

#include <string>
#include <list>
#include <queue>
#include <vector>
#include <complex>
#include <set>

/////////
#define REP(i, x, n) for(int i = x; i < n; i++)
#define rep(i,n) REP(i,0,n)
#define P(p) cout<<(p)<<endl;
/////////
typedef long long LL;
typedef long double LD;
/////////
using namespace::std;
/////////


int main(void){
    std::cin.tie(0); 
    std::ios::sync_with_stdio(false);
    std::cout << std::fixed;//
    //cout << setprecision(6);//
    
	int N;
	cin>>N;
	vector<int> A,B;
	int t;
	rep(i,N){
		cin>>t;
		A.push_back(t);
	}
	rep(i,N){
		cin>>t;
		B.push_back(t);
	}

	sort( A.begin(),A.end() );
	sort( B.begin(),B.end() );
	int Awin = 0;
	int vsAB = 0;
	int Apoint,Bpoint,draw;
	do{
		do{
			Apoint=0;
			Bpoint=0;
			draw  =0;
			for(int i=0;i<N;++i){
				if(A[i]>B[i]){
					++Apoint;
				}else if(B[i]>A[i]){
					++Bpoint;
				}else{
					++draw;
				}
			}
			/////
			++vsAB;
			if(Apoint>Bpoint){
				++Awin;
			}

		}while(next_permutation(B.begin(),B.end()) );
	}while(next_permutation(A.begin(),A.end()) );


	P(1.0*Awin/(1.0*vsAB));
    return 0;
}