using System;

internal static class Program
{
    private static long Calculate(long first, long second)
    {
        return (second + 1)*(first) + second;
    }

    public static void Main(string[] args)
    {
        var n = int.Parse(Console.ReadLine());
        if (n%2 == 1)
        {
            var first = Calculate(n/2 + 1, n/2);
            var second = Calculate(n / 2, n / 2 + 1);
            Console.WriteLine(Math.Max(first, second));
        }
        else
        {
            Console.WriteLine(Calculate(n/2,n/2));
        }
    }
}