import java.util.*;
 

public class Main {
	
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int x= sc.nextInt();
		int y=sc.nextInt();
		double l=sc.nextDouble();
		int ans=0;
		if(y>=0){
			ans+=(int)Math.ceil(y/l);
			if(x!=0){
				ans+=1+(int)Math.ceil(Math.abs(x)/l);
			}
		}else{
			ans=(int)Math.ceil(Math.abs(y)/l);
			if(x!=0){
				ans+=2+(int)Math.ceil(Math.abs(x)/l);
			}
		}
		System.out.println(ans);
	}
}