I am new to using regular expressions for rewriting URL's in htaccess

I need to redirect mysite.com/123 to mysite.com/, IF cookie named 'ref' is set.

my current htaccess is:

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteCond %{HTTP_COOKIE} ref=true [NC]
RewriteRule ^/([0-9]+)/$ http://www.mysite.com
</IfModule>

The goal is that when someone enters site with: mysite.com/111(some number) that they are redirected to the home page of the site after the cookie is set.

Be nice... I'm new! ;o)