#region ZIPPER
using System;
using System.Collections.Generic;
using System.Collections;
using System.Linq;
using System.Text;
using System.Numerics;
using sc = Scanner;
class Program
{
    static void Main(string[] args)
    {
        Solver solver = new Solver();
        solver.Solve();
#if DEBUG
        System.Console.WriteLine("続行するには何かキーを押してください．．．");
        System.Console.ReadKey();
#endif

    }
}
/// <summary>
/// Java風のスキャナー，自作（某最速の人を参考）
/// </summary>
public static class Scanner
{
    public static string NextString()
    {
        string tmp = "";
        while (true)
        {
            int readData;
            string data;
            readData = Console.Read();
            if (readData == -1) //EOF
            {
                break;
            }
            data = char.ConvertFromUtf32(readData);
            if (data == " " || data == "\n")
            {
                break;
            }
            tmp += data;
        }
        return tmp;
    }
    public static int NextInt()
    {
        string tmp = "";
        while (true)
        {
            int readData;
            string data;
            readData = Console.Read();
            if (readData == -1) //EOF
            {
                break;
            }
            data = char.ConvertFromUtf32(readData);
            if (data == " " || data == "\n")
            {
                break;
            }
            tmp += data;
        }
        return int.Parse(tmp);
    }
    public static long NextLong()
    {
        string tmp = "";
        while (true)
        {
            int readData;
            string data;
            readData = Console.Read();
            if (readData == -1) //EOF
            {
                break;
            }
            data = char.ConvertFromUtf32(readData);
            if (data == " " || data == "\n")
            {
                break;
            }
            tmp += data;
        }
        return long.Parse(tmp);
    }
    public static double NextDouble()
    {
        string tmp = "";
        while (true)
        {
            int readData;
            string data;
            readData = Console.Read();
            if (readData == -1) //EOF
            {
                break;
            }
            data = char.ConvertFromUtf32(readData);
            if (data == " " || data == "\n")
            {
                break;
            }
            tmp += data;
        }
        return double.Parse(tmp);
    }

    public static string[] NextStrArray()
    {
        return Console.ReadLine().Split(' ');
    }
    public static int[] NextIntArray()
    {

        string[] s = NextStrArray();
        int[] a = new int[s.Length];
        for (int i = 0; i < a.Length; i++)
        {
            a[i] = int.Parse(s[i]);
        }
        return a;
    }
    public static long[] NextLongArray()
    {
        string[] s = NextStrArray();
        long[] a = new long[s.Length];
        for (int i = 0; i < a.Length; i++)
        {
            a[i] = long.Parse(s[i]);
        }
        return a;
    }
    public static double[] NextDoubleArray()
    {
        string[] s = NextStrArray();
        double[] a = new double[s.Length];
        for (int i = 0; i < a.Length; i++)
        {
            a[i] = double.Parse(s[i]);
        }
        return a;
    }
}
#endregion ZIPPER

public class Solver
{
#region IGNORE_ME
    public Solver()
    {
        //こんすとらくたん　きにしなくてよろしい
    }
#endregion IGNORE_ME

#region FIELD

#endregion FIELD

    public void Solve()
    {
        int a = sc.NextInt();
        double[] p = new double[3];
        for (int i = 0; i < 3; i++)
        {
            p[i] = 1.0 * sc.NextInt() / 100;
        }
        double[,] dp = new double[81, 14];
        for (int i = 0; i < 14; i++)
        {
            dp[a, i] = 1;
        }
        for (int i = a; i < 80; i++)
        {
            for (int j = 1; j < 13; j++)
            {
                double ryosidenon = (1.0-dp[i,j-1])*(1.0-dp[i,j+1]);
                double ryosideari = dp[i,j-1]*dp[i,j+1];
                dp[i + 1, j] =
                    dp[i,j]
                    *(
                    ryosideari * (1-p[2])
                    + ryosidenon * (1-p[0])
                    + (1 - ryosideari - ryosidenon) *(1- p[1])
                    );
#if DEBUG
                Console.WriteLine("{0} {1} {2}",ryosideari,ryosidenon,1.0-ryosideari-ryosidenon);
#endif 
            }
            dp[i + 1, 0] = dp[i,0]*(dp[i, 1] * (1 - p[1]) + (1 - dp[i, 1]) * (1 - p[0]));
            dp[i + 1, 13] = dp[i,13]*(dp[i , 12] * (1 - p[1]) + (1 - dp[i , 12]) * (1 - p[0]));

        }
        double answer = 0;
        for (int i = 0; i < 14; i++)
        {
            answer += 2* dp[80, i];
        }
        Console.WriteLine(answer);
#if DEBUG
        Console.WriteLine("");//local check
#endif
    }

}