using System;

class test2
{
    static void Main()
    {
        double x = double.Parse(Console.ReadLine());
        double y = double.Parse(Console.ReadLine());
        double l = double.Parse(Console.ReadLine());
        int movecnt = 0;
        double a, b, c;

        a = Math.Abs(x) / l;
        b = Math.Abs(y) / l;
        c= Math.Ceiling(a)+Math.Ceiling(b);
        movecnt = (int)c;

        if (x != 0)
        {
            movecnt = movecnt + 1;
        }
        else if (x == 0 && y < 0)
        {
            movecnt = movecnt + 1;
        }
        if (y < 0)
        {
            movecnt = movecnt + 1;
        }
        Console.WriteLine(movecnt);
    }
}