import java.util.Scanner;

public class Exercises13{
  public static void main (String[] args){

    Scanner sc = new Scanner(System.in);

    int x = sc.nextInt();

    int y = sc.nextInt();

    int maxMove = sc.nextInt();

    int oderCount = 0;

    if (y >= 0){
      double count = Math.ceil((double)y / (double)maxMove);
      oderCount += (int)count;

      // 方向転換
      // oderCount += 1;

      if (x > 0){
        oderCount += 1;
        count = Math.ceil((double)x / (double)maxMove);
        oderCount += (int)count;
      }else if (x < 0){
        oderCount += 1;
        count = Math.ceil((double)x / (double)maxMove * -1);
        oderCount += (int)count;
      }
    }else{
      oderCount += 1;

      if (x > 0){
        double count = Math.ceil((double)x / (double)maxMove);
        oderCount += (int)count;
      }else{
        double count = Math.ceil((double)x / (double)maxMove * -1);
        oderCount += (int)count;
      }

      oderCount += 1;

      double count = Math.ceil((double)y / (double)maxMove * -1);
      oderCount += (int)count;

    }

    System.out.println(oderCount);
  }
}