using System;
public class Hello
{
    public static void Main()
    {
        //var sr = new System.IO.StreamReader("test.txt");
        //System.Console.SetIn(sr);

        string line = System.Console.ReadLine().Trim();
        int X = int.Parse(line);
        X = Math.Abs(X);
        line = System.Console.ReadLine().Trim();
        int Y = int.Parse(line);
        line = System.Console.ReadLine().Trim();
        int L = int.Parse(line);

        int count = 0;


        if (Y >= 0)
        {
            count += (int)(Math.Ceiling((double)Y / (double)L));

            if (X != 0)
            {
                count += (int)(Math.Ceiling((double)X / (double)L)) + 1;

                System.Console.WriteLine(count);
                return;
            }
            else
            {
                System.Console.WriteLine(count);
                return;
            }
        }
        else
        {
            Y = Math.Abs(Y);
            count += (int)(Math.Ceiling((double)X / (double)L) + 1);
            count += (int)(Math.Ceiling((double)Y / (double)L) + 1);
            System.Console.WriteLine(count);
            return;
        }
    }
}