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

namespace yukicoder
{
    public class Program
    {
        public static void Main()
        {
            var d = int.Parse(Console.ReadLine());
            var k = d / 4;
            if (d % 4 < 2)
            {
                Console.WriteLine(k*k);
            }
            else
            {
                Console.WriteLine(k * (k + 1));
            }
        }
    }
}