package main

import (
	"bufio"
	"fmt"
	"os"
	"sort"
	"strconv"
)

func out(x ...interface{}) {
	fmt.Println(x...)
}

var sc = bufio.NewScanner(os.Stdin)

func getInt() int {
	sc.Scan()
	i, e := strconv.Atoi(sc.Text())
	if e != nil {
		panic(e)
	}
	return i
}

func getInts(N int) []int {
	ret := make([]int, N)
	for i := 0; i < N; i++ {
		ret[i] = getInt()
	}
	return ret
}

func getString() string {
	sc.Scan()
	return sc.Text()
}

// min, max, asub, absなど基本関数
func max(a, b int) int {
	if a > b {
		return a
	}
	return b
}

func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}

func asub(a, b int) int {
	if a > b {
		return a - b
	}
	return b - a
}

func abs(a int) int {
	if a >= 0 {
		return a
	}
	return -a
}

func lowerBound(a []int, x int) int {
	idx := sort.Search(len(a), func(i int) bool {
		return a[i] >= x
	})
	return idx
}

func upperBound(a []int, x int) int {
	idx := sort.Search(len(a), func(i int) bool {
		return a[i] > x
	})
	return idx
}

func main() {
	sc.Split(bufio.ScanWords)
	Age := getInt()
	P0, P1, P2 := getInt(), getInt(), getInt()
	N := 80 - Age
	p0, p1, p2 := 1.0-float64(P0)/100, 1.0-float64(P1)/100, 1.0-float64(P2)/100
	dp := make([][16]float64, N+1)
	for i := 1; i < 15; i++ {
		dp[0][i] = 1.0
	}

	// out(dp[0])
	for i := 1; i <= N; i++ {
		for j := 1; j < 15; j++ {
			dp[i][j] += (1 - dp[i-1][j-1]) * (1 - dp[i-1][j+1]) * p0
			dp[i][j] += (1 - dp[i-1][j-1]) * dp[i-1][j+1] * p1
			dp[i][j] += dp[i-1][j-1] * (1 - dp[i-1][j+1]) * p1
			dp[i][j] += dp[i-1][j-1] * dp[i-1][j+1] * p2
			dp[i][j] *= dp[i-1][j]
		}
		// out(dp[i])
	}
	ans := 0.0
	for i := 0; i < 16; i++ {
		ans += dp[N][i]
	}
	out(ans * 2)
}