using System;
using System.Collections.Generic;
using System.Linq;
using static System.Console;

class Program
{
    static void Main()
    {
        var X = int.Parse(ReadLine());
        var Y = int.Parse(ReadLine());
        var L = int.Parse(ReadLine());
        WriteLine((X + L - 1) / L + (Y + L - 1) / L + (Y >= 0 ? X == 0 ? 0 : 1 : 2));
    }
}