import java.util.*;

public class Main {
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    // 整数の入力
	int x = sc.nextInt();
	int y = sc.nextInt();
	double l = sc.nextInt();

	double countx = 0;
	double county = 0;
	int countturn = 0;

	countx = Math.ceil(Math.abs(x) / l);
	county = Math.ceil(Math.abs(y) / l);
	//System.out.println(countx);
	//System.out.println(county);

	if(y < 0) countturn = 2;
	else if(x == 0) countturn = 0;
	else countturn = 1;
	//System.out.println(countturn);

	int total = 0;
	total = (int)countx + (int)county + countturn;
	System.out.println(total);
  }
}