Is it necessary to wrap <strong>, <em>, <b>, <i> inside <p> tag, if content is not paragraph?

Question

For example:

This is ok

<div>
    <p>some <strong>long</strong> text</p>
    <strong>- end -</strong>
    <p>some long text</p>
</div>

Or this is more semantically correct?

<div>
    <p>some <strong>long</strong> text</p>
    <p><strong>- end -</strong></p>
    <p>some long text</p>
</div>

Answer 1

Academic answer: both are XHTML-compatible. Practical answer: browsers won't give a sh@t about it