using System;
using System.IO;
using System.Linq;

namespace yukicore
{
    internal class Program
    {
        private static void Main(string[] args)
        {
            int count = 0;
            int x = int.Parse(Console.ReadLine());
            int y = int.Parse(Console.ReadLine());

            if (x < 0) count=2;
           
            else if (y != 0) count = 1;

            int dist = int.Parse(Console.ReadLine());
           
            count += upper(1.0 * x / dist);
            count += upper(1.0 * y / dist);
            Console.WriteLine(count);
        }

        static int upper(double n)
        {
            if (n % 1 == 0)
                return(int) n;
            else
                return(int) Math.Floor(n) + 1;
        }
    }
}