private ArrayList<Position> findBoxes(ArrayList<String> board)
    {
        ArrayList<Position> boxes = new ArrayList<Position>();
        for (int y = 0; y < board.size(); ++y)
        {
            for (int x = 0; x < board.get(y).length(); ++x)
            {
                char c = board.get(y).charAt(x);
                if (c == '$' || c == '*')
                    boxes.add(new Position(x, y));
            }
        }
        return boxes;
    }