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

namespace YukiCoder
{
    class Program
    {
        static void Main(string[] args)
        {
            int nx = int.Parse(Console.ReadLine());
            int ny = int.Parse(Console.ReadLine());
            int nl = int.Parse(Console.ReadLine());

            int nn = (Math.Abs(nx) + nl - 1) / nl
                   + (Math.Abs(ny) + nl - 1) / nl;

            if (ny < 0)         nn += 2;
            else if (nx != 0)   nn += 1;
            
            Console.WriteLine(nn);
            Console.ReadLine();
        }
    }
}