import java.util.Scanner;
	

public class Main{
	
	
	public static void main(String args[])throws Exception{
		
		Scanner sc = new Scanner(System.in);
		int X = sc.nextInt();
		int Y = sc.nextInt();
		int L = sc.nextInt();
		X = Math.abs(X);
		int ans = 0;
		if(Y>0){
			ans += (Y-1)/L+1;
			if(X>0){
				ans += (X-1)/L+2;
			}
		}else if(Y<0){
			ans += 2;
			Y = Math.abs(Y);
			if(X>0){
				ans += (X-1)/L+1;
			}
			ans += (Y-1)/L+1;
		}else{
			if(X>0){
				ans += (X-1)/L+2;
			}
		}
		System.out.println(ans);
		
	}
}