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HSTS and double redirect

Hello Users, I was testing my website here <a href="https://hstspreload.org" title="https://hstspreload.org">https://hstspreload.org</a> and I
received this error:

Error: HTTP redirects to www first

<a href="http://example" title="http://example">http://example</a> (HTTP) should immediately redirect to <a href="https://example" title="https://example">https://example</a>
(HTTPS) before adding the www subdomain. Right now, the first redirect is
to <a href="https://www.example" title="https://www.example">https://www.example</a>. The extra redirect is required to ensure that any
browser which supports HSTS will record the HSTS entry for the top level
domain, not just the subdomain.

As far as I can understand, the redirect, to be valid, should be done this
way:

1. <a href="http://example" title="http://example">http://example</a> (this is what the user enters in the address bar)
2. <a href="https://example" title="https://example">https://example</a> (first redirect, to HTTPS)
3. <a href="https://www.example" title="https://www.example">https://www.example</a> (second redirect, to subdomain www)

At the moment, this is my htaccess code causing the redirect (the htaccess
is the ONLY thing I can edit because I'm in a very restrictive shared
hosting environment):

RewriteCond %{SERVER_PORT} 80
RewriteRule ^(.*)$ https://www.example.com/$1 [R,L]

Is it possible to insert another redirect here? Is it advisable? How could
I do?

Thanks anybody