import java.util.Scanner;

public class Main48 {
	public static void main(String[] args) {
		Main48 p = new Main48();
	}

	public Main48() {
		Scanner sc = new Scanner(System.in);
		int x = sc.nextInt();
		int y = sc.nextInt();
		int l = sc.nextInt();
		solve(x, y, l);
	}

	public void solve(int x, int y, int l) {
		int res = x!=0 ? (Math.abs(x)-1)/l + 1 : 0;
		res += y!=0 ? (Math.abs(y)-1)/l + 1 : 0;
		
		if(y<0)
			res+=2;
		else if(Math.abs(x)>0)
			res++;
		
		System.out.println(res);
	}

}