int i = 0;
    int acs;
    Asteroid(int a) {
        if(a > 2) acs = a;
        else acs = 2;
    }

    public void act() 
    {

        if((this.getX() < 5) || (this.getX() > getWorld().getWidth()-5) || (this.getY() == 399)) {
            getWorld().removeObject(this);
        }

        if(i == 0) {
            this.turnTowards(Greenfoot.getRandomNumber(getWorld().getWidth()),getWorld().getHeight()); i++;
        }
        this.move(acs/2);

    }