using System;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        int d = ri();

        if (d % 2 == 1) d--;

        if (d % 4 == 0) Console.WriteLine(d * d / 16);
        else Console.WriteLine((d * d / 4 - 1) / 4);
    }

    #region Scan
    static int ri() { return int.Parse(Console.ReadLine()); }
    static long rl() { return long.Parse(Console.ReadLine()); }
    static double rd() { return double.Parse(Console.ReadLine()); }
    static string rs() { return Console.ReadLine(); }
    static int[] ria(int n) { return Console.ReadLine().Trim().Split().Select(int.Parse).ToArray(); }
    static long[] rla(int n) { return Console.ReadLine().Trim().Split().Select(long.Parse).ToArray(); }
    static double[] rda(int n) { return Console.ReadLine().Trim().Split().Select(double.Parse).ToArray(); }
    static string[] rsa(int n) { return Console.ReadLine().Trim().Split(); }
    static void mul(out int a, out int b) { var arr = ria(2); a = arr[0]; b = arr[1]; }
    public void mul(out int a, out int b, out int c) { var arr = ria(3); a = arr[0]; b = arr[1]; c = arr[2]; }
    public void mul(out int a, out int b, out int c, out int d) { var arr = ria(4); a = arr[0]; b = arr[1]; c = arr[2]; d = arr[3]; }
    #endregion
}