using System;
using System.Linq;

class Program
{
    static void Main(string[] args)
    {
        int ew = int.Parse(Console.ReadLine());
        int ns = int.Parse(Console.ReadLine());
        int range = int.Parse(Console.ReadLine());
        int count = 0;

        if (ns < 0)
        {
            count += 2;
        }
        else if (Math.Abs(ew) > 0)
        {
            count += 1;
        }

        if (Math.Abs(ew) % range == 0)
        {
            count += Math.Abs(ew) / range;
        }
        else
        {
            count += Math.Abs(ew) / range + 1;
        }

        if (Math.Abs(ns) % range == 0)
        {
            count += Math.Abs(ns) / range;
        }
        else
        {
            count += Math.Abs(ns) / range + 1;
        }

        Console.WriteLine(count);
        Console.ReadLine();
    }
}