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

namespace template
{
    class Program
    {
        static void Main(string[] args)
        {
            int x = int.Parse(Console.ReadLine());
            int y = int.Parse(Console.ReadLine());
            int n = int.Parse(Console.ReadLine());
            int ret = (Math.Abs(x) - 1) / n + 1;
            ret += (Math.Abs(y) - 1) / n + 1;
            if (x != 0) ret++;
            if (y < 0) ret += 2;
            Console.WriteLine(ret);
        }
    }
}