>PowerPoint</div>
                    <div>
                        <span>M1</span>
                        <div style="width:120px;">
                            <div>sub1</div>
                            <div>sub2</div>
                            <div>
                                <span>Sub</span>
                                <div style="width:80px;">
                                    <div onclick="javascript:alert('sub21')">sub21</div>
                                    <div>sub22</div>
      