I successfully get string first\_slide, second\_slide etc, I want to get ID form that string: 
like on click: the development
i want to get its id: 1,

```
            <ul>
                <li><a href="#first_slide" id="1">the development</a></li>
                <li><a href="#second_slide" id="2">the design</a></li>
                <li><a href="#third_slide" id="3">the locate</a></li>
                <li><a href="#fourth_slide" id="4">the layout</a></li>
                <li><a href="#fifth_slide" id="5">the team</a></li>
                <li><a href="#sixth_slide" id="6">contact</a></li>
            </ul>

```