#include <stdio.h>

int A_kati = 0;
int game_num = 0;

void func(int count, int N, int A_already[10], int B_already[10], int A_num[10], int B_num[10], int A_win, int B_win){
    if(count >= N){
        game_num++;
        if(A_win > B_win){
            A_kati++;
        }
        return;
    }
    for(int i = 0; i < N; i++){
        if(A_already[i] == 0){
            for(int j = 0; j < N; j++){
                if(B_already[j] == 0){
                    B_already[j] = 1;
                    A_already[i] = 1;
                    if(A_num[i] > B_num[j]){
                        A_win++;
                    }else{
                        B_win++;
                    }
                    func(count + 1, N, A_already, B_already, A_num, B_num, A_win, B_win);
                    if(A_num[i] > B_num[j]){
                        A_win--;
                    }else{
                        B_win--;
                    }
                    B_already[j] = 0;
                    A_already[i] = 0;
                }
            }
        }
    }
    
}

int main(int argc, const char * argv[]) {
    int N = 0;
    
    scanf("%d", &N);
    int A_num[10];
    int B_num[10];
    int A_already[10];
    int B_already[10];
    
    for(int i = 0; i < N; i++){
        scanf("%d",&A_num[i]);
    }
    for(int i = 0; i < N; i++){
        scanf("%d",&B_num[i]);
    }
    
    for(int i = 0; i < 10; i++){
        A_already[i] = B_already[i] = 0;
    }
    
    func(0, N, A_already, B_already, A_num, B_num, 0, 0);
    
    printf("%lf\n", (double)A_kati / (double)game_num);
    
    return 0;
}