using System;
using System.IO;
using System.Linq;
using System.Text;
using System.Diagnostics;
using System.Collections.Generic;
using System.Text.RegularExpressions;
using Enu = System.Linq.Enumerable;

class Program
{
    static readonly int NumTeeth = 14;
    static readonly int Target = 80;
    double[] BadProb;
    double?[, ,] memo;

    void Solve()
    {
        int Age = reader.Int();
        BadProb = Enu.Range(0, 3).Select(i => reader.Double() / 100).ToArray();
        int rem = Target - Age;
        memo = new double?[rem + 1, NumTeeth + 1, 2];
        double ans = 2 * Rec(rem, NumTeeth, 1);
        Console.WriteLine(ans);
    }

    private double Rec(int year, int len, int isLeftBad)
    {
        if (year == 0 || len == 0) return len;
        if (len == 1) return (1 - BadProb[1 - isLeftBad]) * Rec(year - 1, 1, 1);
        if (memo[year, len, isLeftBad].HasValue) return memo[year, len, isLeftBad].Value;
        double res = 0;
        double good = 1;

        for (int firstBad = 0; firstBad < len; firstBad++)
        {
            double p = (firstBad == 0 && isLeftBad == 1 || firstBad == len - 1) ? BadProb[1] : BadProb[2];
            res += good * p * Rec(year - 1, firstBad, 1);
            res += good * p * Rec(year, len - 1 - firstBad, 0);
            good *= 1 - p;
        }
        res += good * Rec(year - 1, len, 1);
        memo[year, len, isLeftBad] = res;

        return res;
    }




    Reader reader = new Reader(Console.In);
    static void Main()
    {
        new Program().Solve();
    }
}

class Reader
{
    private readonly TextReader reader;
    private readonly char[] separator = { ' ' };
    private readonly StringSplitOptions removeOp = StringSplitOptions.RemoveEmptyEntries;
    private string[] A = new string[0];
    private int i;

    public Reader(TextReader r) { reader = r; }
    public Reader(string file) { reader = new StreamReader(file); }
    public bool HasNext() { return Enqueue(); }
    public string String() { return Dequeue(); }
    public int Int() { return int.Parse(Dequeue()); }
    public long Long() { return long.Parse(Dequeue()); }
    public double Double() { return double.Parse(Dequeue()); }
    public int[] IntLine() { var s = Line(); return s == "" ? new int[0] : Array.ConvertAll(Split(s), int.Parse); }
    public int[] IntArray(int N) { return Enu.Range(0, N).Select(i => Int()).ToArray(); }
    public int[][] IntGrid(int H) { return Enu.Range(0, H).Select(i => IntLine()).ToArray(); }
    public string[] StringArray(int N) { return Enu.Range(0, N).Select(i => Line()).ToArray(); }
    public string Line() { return reader.ReadLine().Trim(); }
    private string[] Split(string s) { return s.Split(separator, removeOp); }
    private bool Enqueue()
    {
        if (i < A.Length) return true;
        string line = reader.ReadLine();
        if (line == null) return false;
        if (line == "") return Enqueue();
        A = Split(line);
        i = 0;
        return true;
    }
    private string Dequeue() { Enqueue(); return A[i++]; }
}