import java.util.*;
public class Test12 {
  public static void main(String[] args){
    Scanner sc=new Scanner(System.in);
    String[] line;
    line=sc.nextLine().split(" ");
    int x=Integer.parseInt(line[0]);
    line=sc.nextLine().split(" ");
    int y=Integer.parseInt(line[0]);
    line=sc.nextLine().split(" ");
    int l=Integer.parseInt(line[0]);
    int turn=0;
    if(x!=0){
      turn=1;
      if(x<0) x*=-1;
    }
    if(y<0){
      turn=2;
      y*=-1;
    }
    turn+=(x+l-1)/l;
    turn+=(y+l-1)/l;
    System.out.println(turn);
    sc.close();
  }
}