using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    static string[] SList(int n) => Enumerable.Repeat(0, n).Select(_ => ReadLine()).ToArray();
    static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var n = NN;
        var c = 2903.83603252175836913358;
        WriteLine(c / 11 / 11 / 11 * n * n * n);
    }
}