#include <iostream>
#include <algorithm>

using namespace std;

int main(){
    int N;
    cin>>N;
    int a[4];
    int b[4];
    for(int i=0;i<N;i++){
        cin>>a[i];
    }
        for(int i=0;i<N;i++){
        cin>>b[i];
    }
    int index[]={0,1,2,3};
    int all=0;
    int awincount=0;

    do{
        int awin=0;
        int bwin=0;
        
        for(int i=0;i<N;i++){
            if(a[index[i]]>b[i]){
                awin++;
            } else{
                bwin++;
            }
        }

        if(awin>bwin){
            awincount++;
        }
        all++;
    }while(next_permutation(index, index + N));

    cout<<(double)awincount/all<<endl;
    return 0;
}