htaccess - do not rewrite in this case

My access file looks like this:

RewriteEngine On
RewriteCond %{REQUEST_FILENAME} -s [OR]
开发者_如何学CRewriteCond %{REQUEST_FILENAME} -l [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^.*$ - [NC,L]
RewriteRule ^.*$ index.php [NC,L]

But I have a directory called facebook that I want to access as usuall through the URL http://mysite.com/facebook. What do I need to add to the above so that it ignores (does not rewrite) this directory?

---

add:

RewriteEngine On
RewriteCond %{REQUEST_FILENAME} -s [OR]
RewriteCond %{REQUEST_FILENAME} -l [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^.*$ - [NC,L]
RewriteCond %{REQUEST_URI}  !^/facebook
RewriteRule ^.*$ index.php [NC,L]