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

namespace Application
{
	class MainClass
	{
		public static void Main (string[] args)
		{
			var X = readInt ();
			var Y = readInt ();
			var L = readInt ();

			var count = 0;
			if (0 < Y) {
				if (X != 0){
					count++;
				}
			} else if (X != 0){
				count++;
				if (Y < 0){
					count++;
				}
			} else if ( Y < 0) {
				count +=2;
			}

			count += Convert.ToInt32(Math.Ceiling(Math.Abs(X) / (double)L));
            count += Convert.ToInt32(Math.Ceiling(Math.Abs(Y) / (double)L));
            
			writeLine (count);
		}

		static void writeLine (object o)
		{
			System.Console.WriteLine (o.ToString ());
		}

		static string readItem ()
		{
			return readItems (' ') [0];
		}

		static String[] readItems (char c)
		{
			return System.Console.ReadLine ().Split (c);
		}

		static int readInt ()
		{
			return readInts (' ') [0];
		}

		static int[] readInts (char c)
		{
			return readItems (c).Select (x => int.Parse (x)).ToArray ();
		}
	}
}