using System;

class S18_robot{
  public static int Main(string[] args){
    int x, y, l;
    int count = 0;

    x = int.Parse(Console.ReadLine());
    y = int.Parse(Console.ReadLine());
    l = int.Parse(Console.ReadLine());

    if(y < 0){
      count += 2;
    }else if(Math.Abs(x) > 0){
      count += 1;
    }

    if(Math.Abs(x) % l == 0)
      count += Math.Abs(x) / l;
    else
      count += Math.Abs(x) / l + 1;

    if(Math.Abs(y) % l == 0)
      count += Math.Abs(y) / l;
    else
      count += Math.Abs(y) / l + 1;

    Console.WriteLine("{0}",count);
    return 0;
  }
}