using System;
using System.Collections.Generic;

class Program
{
    static string InputPattern = "InputX";

    static List<string> GetInputList()
    {
        var WillReturn = new List<string>();

        if (InputPattern == "Input1") {
            WillReturn.Add("1");
            //0
            //1回投げて全部揃うことはありません
        }
        else if (InputPattern == "Input2") {
            WillReturn.Add("6");
            //0.015432098765432
            //(1/6)の6乗 * 6の階乗
        }
        else if (InputPattern == "Input3") {
            WillReturn.Add("7");
            //0.054012345
        }
        else if (InputPattern == "Input4") {
            WillReturn.Add("50");
            //0.99934071
            //このくらいになるとほぼ確実に全て出ますね
        }
        else {
            string wkStr;
            while ((wkStr = Console.ReadLine()) != null) WillReturn.Add(wkStr);
        }
        return WillReturn;
    }

    static void Main()
    {
        List<string> InputList = GetInputList();
        int N = int.Parse(InputList[0]);

        //確率[登場した目の数]なDP表
        double[] PrevDP = new double[7];
        PrevDP[0] = 1D;

        for (int I = 1; I <= N; I++) {
            double[] CurrDP = new double[7];

            for (int J = 0; J <= 6; J++) {
                //登場した目の数が増えない確率
                double HuenaiP = J / 6D;
                CurrDP[J] += PrevDP[J] * HuenaiP;

                //登場した目の数が1増える確率
                double HueruP = 1D - HuenaiP;

                if (J <= 5) {
                    CurrDP[J + 1] += PrevDP[J] * HueruP;
                }
            }
            PrevDP = CurrDP;
        }
        Console.WriteLine(PrevDP[6]);
    }
}