import java.util.Scanner;

public class No48 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);
		int x = sc.nextInt();
		int y = sc.nextInt();
		int l = sc.nextInt();
		
		x=Math.abs(x);
		y=Math.abs(y);
		
		int mx,my;
		
		if(x%l==0){
			mx=x/l;
		}else{
			mx=x/l+1;
		}
		
		if(y%l==0){
			my=y/l;
		}else{
			my=y/l+1;
		}
		
		if(x == 0&&y == 0){
			System.out.println(0);
		}else if(x == 0 && y < 0){
			System.out.println(my + 1);
		}else if(x != 0 && y==0){
			System.out.println(mx);
		}else{
			System.out.println(mx+my+1);
		}
		
		
	}
		
}