using System;

namespace No48
{
    class Program
    {
        static void Main(string[] args)
        {
            var X = double.Parse(Console.ReadLine());
            var Y = double.Parse(Console.ReadLine());
            var L = double.Parse(Console.ReadLine());

            var result = 0;
            result += (int)Math.Ceiling(Math.Abs(X) / L);
            result += (int)Math.Ceiling(Math.Abs(Y) / L);

            if (Y < 0)
            {
                result += 2;
            }
            else
            {
                if (X != 0) result += 1;
            }

            Console.Write(result);
        }
    }
}