import java.io.*;
import java.util.*;
/*yukicoder No.48 ロボットの操縦*/
class No48{
  public static void main(String[] args){
    Scanner scan = new Scanner(System.in);
    double x = scan.nextInt();
    double y = scan.nextInt();
    double l = scan.nextInt();
    double count = 0;
    if(y<0){
      y = -y;
      count += 2;
    }else if(x==0){
    }else{
      count++;
    }
    count += Math.ceil(y/l);
    if(x<0) x = -x;
    count += Math.ceil(x/l);
    System.out.println((int)count);
  }
}