using System;

class Program
{
    static void Main()
    {
        int X = int.Parse(Console.ReadLine());
        int Y = int.Parse(Console.ReadLine());
        int L = int.Parse(Console.ReadLine());
        int x = 0, y = 0, dir = 0, count = 0;
        if(0 < Y)
        {
            while(y < Y)
            {
                y += L;
                count++;
            }
        }
        if(X < 0)
        {
            count++;
            while(X < x)
            {
                x -= L;
                count++;
            }
        }
        else if(0 < X)
        {
            count++;
            while(x < X)
            {
                x += L;
                count++;
            }
        }
        else if(X == 0 && Y < 0)
        {
            count++;
        }
        if(Y < 0)
        {
            while(Y < y)
            {
                y -= L;
                count++;
            }
        }
        Console.WriteLine($"{count}");
    }
}