using System;

class Program
{
    static void Main()
    {
        double x = double.Parse(Console.ReadLine());
        double y = double.Parse(Console.ReadLine());
        double l = double.Parse(Console.ReadLine());

        int cnt = 0;

        cnt += (int)(Math.Ceiling(Math.Abs(x) / l) + Math.Ceiling(Math.Abs(y) / l));

        if (x != 0) cnt++;
        else if (x == 0 && y < 0) cnt++;
        if (y < 0) cnt++;


        Console.WriteLine(cnt);
    }
}