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

namespace pj6
{
    class Program
    {
        static void Main(string[] args)
        {
            int X = int.Parse(Console.ReadLine());

            int Y = int.Parse(Console.ReadLine());

            int L = int.Parse(Console.ReadLine());

            int count = 0;

            if(X < 0)
            {
              X =  X * -1;
            }

            if (Y < 0)
            {
                Y = Y * -1;
                count++;
                if(X == 0)
                {
                    count++;
                }
            }

            if(X > 0)
            {
                count++;
            }

            while(X > 0)
            {
                X -= L;
                count++;
            }

            while(Y > 0)
            {
                Y -= L;
                count++;
            }

            Console.WriteLine(count);
        }
    }
}