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

namespace yukicoderTest
{
    class Program
    {
        static void Main(string[] args)
        {
            string x = Console.ReadLine();
            string y = Console.ReadLine();
            string l = Console.ReadLine();
            int we = int.Parse(x);
            int ns = int.Parse(y);
            int forward = int.Parse(l);
            int posiwe = 0;
            int posins = 0;
            int command = 0;
            while (posiwe!=we||posins!=ns)
            {
                if (ns < 0 && posins != ns)
                {
                    command = command + 2;
                    if (ns - posins < forward)
                    {
                        posins = ns;
                        command++;
                    }
                    else
                    {
                        posins = posins - forward;
                        command++;
                    }
                }

                else if (ns > 0 && posins != ns)
                {
                    if (ns - posins < forward)
                    {
                        posins = ns;
                        command++;
                    }
                    else
                    {
                        posins = posins + forward;
                        command++;
                    }
                }
                if (we < 0&&posiwe!=we)
                {
                    command++;
                    if (we - posiwe < forward)
                    {
                        posiwe = we;
                        command++;
                    }
                    else
                    {
                        posiwe = posiwe - forward;
                        command++;
                    }
                }
                else if (we > 0&&posiwe != we)
                {
                    command++;
                    if (we - posiwe < forward)
                    {
                        posiwe = we;
                        command++;
                    }
                    else
                    {
                        posiwe = posiwe + forward;
                        command++;
                    }
                }
                
                
            }
            Console.WriteLine(command);
        }
    }
}