using System;

namespace ConsoleApplication10
{
    class Program
    {
        static void Main(string[] args)
        {
            Vector2 dest = new Vector2(0, 0);
            dest.X = int.Parse(Console.ReadLine());
            dest.Y = int.Parse(Console.ReadLine());
            int speedOnCell = int.Parse(Console.ReadLine());
            int VerticalStep = Math.Abs(dest.Y);
            int HorizontalStep = Math.Abs(dest.X);

            if (VerticalStep % speedOnCell == 0) VerticalStep /= speedOnCell;
            else  VerticalStep = (VerticalStep - (VerticalStep % speedOnCell)) / speedOnCell + 1;

            if (HorizontalStep % speedOnCell == 0) HorizontalStep /= speedOnCell;
            else HorizontalStep = (HorizontalStep - (HorizontalStep % speedOnCell)) / speedOnCell + 1;



            if (dest.X == 0 && dest.Y == 0) Console.WriteLine(0.ToString());
            else if (dest.Y > 0)
            {
                if (dest.X == 0)
                {
                    Console.WriteLine(VerticalStep.ToString());
                }
                else
                {
                    Console.WriteLine((VerticalStep + HorizontalStep + 1).ToString());
                }
            }
            else if (dest.Y == 0)
            {
                Console.WriteLine((1 + HorizontalStep).ToString());
            }
            else
            {
                Console.WriteLine((HorizontalStep + VerticalStep + 2).ToString());
            }
        }
    }

    class Vector2
    {
        public int X { get; set; }
        public int Y { get; set; }
        public Vector2(int x,int y)
        {
            X = x;
            Y = y;
        }
        
    }
}