Please refer this
https://experienceleaguecommunities.adobe.com/t5/adobe-experience-manager/how-to-use-an-integer-valu...
If you are dealing with dynamic value then you can use below code -
<ul data-sly-list="${currentPage.listChildren @ begin = 0, end = 3}">
<li>${item.title}</li>
</ul>
[
<!--/* if you want to first 5 elements of the list */-->
<ul data-sly-list="${currentPage.listChildren @ begin = 0, end = 4}"> <li>${item.title}</li> </ul>
<!--/* if you want to see from 5th to 10th element */-->
<div data-sly-repeat="${currentPage.listChildren @ begin = 4, end = 9}"> <div>${item.title}</div> </div>
]
https://www.myareapage.com/3-new-features-of-htl-in-aem-6-5/
Hope these will help you.