import java.util.Scanner;
class Main{
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int x = sc.nextInt() , y=sc.nextInt() , l = sc.nextInt() , count = 0, muki = 0;
		//北
		if(y > 0) {
			count += y / l;
			if(y % l != 0)count++;//端数!
		}
		//東(右)
		if(x > 0) {
			count++;//向き変える(右向く)
			count += x / l;
			if(x % l != 0)count++;//端数!
			muki = 1;
		}else if(x < 0) {//西(左)
			count++;//向き変える(右向く)
			count += (x * -1) / l;
			if((x * -1) % l != 0)count++;//端数!
			muki = 1;
		}
		//南
		if(y < 0) {
			if(muki == 0)count++;//北を向いていたら2回方向転換
			count++;
			count += (y * -1) / l;
			if((y * -1) % l != 0)count++;//端数!
		}
		System.out.println(count);
	}
}