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 cnt = 0;
            if (ns < 0 && we == 0)
            {
                cnt = cnt + 2;
            }
            else if (ns < 0)
            {
                cnt++;
            }
            if (we != 0)
            {
                cnt++;
            }
            
            while (posiwe != we)
            {  
                
                if (we < 0)
                {
                    
                    if ((we * -1) - (posiwe*-1) < forward)
                    {
                        posiwe = we;
                        cnt++;
                    }
                    else
                    {
                        posiwe = posiwe - forward;
                        cnt++;
                    }
                }
                else if (we > 0)
                {
                    
                    if (we - posiwe < forward)
                    {
                        posiwe = we;
                        cnt++;
                    }
                    else
                    {
                        posiwe = posiwe + forward;
                        cnt++;
                    }
                }

            }
            
            while (posins != ns)
            {
                if (ns < 0)
                {

                    if ((ns * -1) - (posins * -1) < forward)
                    {
                        posins = ns;
                        cnt++;
                    }
                    else
                    {
                        posins = posins - forward;
                        cnt++;
                    }
                }
                else if (ns > 0)
                {
                    if (ns - posins < forward)
                    {
                        posins = ns;
                        cnt++;
                    }
                    else
                    {
                        posins = posins + forward;
                        cnt++;
                    }
                }
            }

            Console.WriteLine(cnt);
        }
    }
}