Methodology Structure BEM (Block, Element, Modifier)

What is the correct structure according to the methodology BEM , I am reading the above documentation, though I am still in doubt, as follows:

Example 1:

<nav class="main-nav">
    <ul class="main-menu">
        <li class="main-menu__link"><a href="#">Link 1</a>
        <li class="main-menu__link"><a href="#">Link 2</a>
        <li class="main-menu__link"><a href="#">Link 3</a>
    </ul>
</nav>

Example 2:

<nav class="main-nav">
    <ul class="main-nav__main-menu">
        <li class="main-nav__main-menu__link">
        <li class="main-nav__main-menu__link">
        <li class="main-nav__main-menu__link">
    </ul>
</nav>

What is the correct way, example 1 or example 2?

Note that example 2 is a hierarchy of elements when naming the class, as in example number 1 there is no more direct hierarchy