import java.util.*;

class S18_robot{
  public static void main(String[] args){
    int x, y, l;
    int count = 0;
    Scanner scn = new Scanner(System.in);

    x = scn.nextInt();
    y = scn.nextInt();
    l = scn.nextInt();

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

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

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

    System.out.println(count);
  }
}