package main

import (
	"fmt"
	"math/rand"
	"sort"
	"time"
)

func copySlice(a []int) []int {
	b := make([]int, len(a))
	copy(b, a)
	return b
}

func removeSlice(a []int, x int) []int {
	b := append(a[:x], a[x+1:]...)
	return b
}

func popSlice(a []int, x int) ([]int, int) {
	r := a[x]
	b := removeSlice(a, x)
	return b, r
}

func main() {
	var n int
	var pa, pb float64
	fmt.Scan(&n, &pa, &pb)
	a := make([]int, n)
	b := make([]int, n)
	rand.Seed(time.Now().UnixNano())
	for i := 0; i < n; i++ {
		fmt.Scan(&a[i])
	}
	for i := 0; i < n; i++ {
		fmt.Scan(&b[i])
	}
	sort.Ints(a)
	sort.Ints(b)
	win_a := 0
	win_b := 0
	X := 400000
	for i := 0; i < X; i++ {
		score_a := 0
		score_b := 0
		sub_a := copySlice(a)
		sub_b := copySlice(b)
		for j := 0; j < n; j++ {
			//			fmt.Println(sub_a)
			//			fmt.Println(sub_b)
			ca := 0
			cb := 0
			if j < n-1 {
				if pa > rand.Float64() {
					sub_a, ca = popSlice(sub_a, 0)
				} else {
					sub_a, ca = popSlice(sub_a, rand.Intn(len(sub_a)-1)+1)
				}
				if pb > rand.Float64() {
					sub_b, cb = popSlice(sub_b, 0)
				} else {
					sub_b, cb = popSlice(sub_b, rand.Intn(len(sub_b)-1)+1)
					//					cb = sub_b[rand.Intn(len(sub_b)-1)+1]
				}
			} else {
				ca = sub_a[0]
				cb = sub_b[0]
			}
			if ca > cb {
				score_a += ca + cb
			} else {
				score_b += ca + cb
			}
		}
		if score_a > score_b {
			//			fmt.Println("a WIN!")
			win_a += 1
		} else {
			//			fmt.Println("a LOSE!")
			win_b += 1
		}

	}
	//	fmt.Println(win_a, win_b)
	fmt.Println(float64(win_a) / float64(X))
}