import java.util.Scanner;


public class Main {
	public static void main(String[] a) {
		Scanner s=new Scanner(System.in);
		int X=s.nextInt(),Y=s.nextInt(),L=s.nextInt();
		int H=(int)Math.ceil(Math.abs((double)X/L)),V=(int)Math.ceil(Math.abs((double)Y/L));
		int P=(int)(Math.signum(X)+1+3*(Math.signum(Y)+1));
		System.out.println(H+V+(new int[]{2,2,2,1,0,1,1,0,1})[P]);
	}
}