import java.util.ArrayDeque;
import java.util.Deque;
import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;

public class Main {
    private static int n;
    private static int[] a;
    private static int[] b;
    private static int win = 0;
    private static int match = 0;

    private static void make(Deque<Integer> que) {
        if(que.size() == n) {
            match++;
            int awin = 0;
            int bwin = 0;
            for(int i = 0; i < n; i++) {
                int j = que.poll();
                if(a[i] > b[j]) awin++;
                else bwin++;
            }
            if(awin > bwin) win++;
            return;
        }

        for(int i = 0; i < n; i++) {
            if(!que.contains(i)) {
                Deque<Integer> nque = new ArrayDeque<>();
                for(int j : que) {
                    nque.add(j);
                }
                nque.add(i);
                make(nque);
            }
        }
    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        n = sc.nextInt();
        a = new int[n];
        b = new int[n];
        for(int i = 0; i < n; i++) {
            a[i] = sc.nextInt();
        }
        for(int i = 0; i < n; i++) {
            b[i] = sc.nextInt();
        }

        make(new ArrayDeque<>());
        System.out.println(1.0 * win / match);

        sc.close();
    }
}