import java.util.Scanner;

class no48{
	public static void main(String[] args) {
		Scanner stdIn=new Scanner(System.in);
		int x,y,l,s=0;
		x=stdIn.nextInt();
		y=stdIn.nextInt();
		l=stdIn.nextInt();
		if(y<0) s+=2;
		if(x!=0&&y>=0) s++;
		if(x<0) x=-x;
		if(y<0) y=-y;
		s+=x/l;
		s+=y/l;
		if(x%l!=0) s++;
		if(y%l!=0) s++;
		System.out.print(s);
	}
}