I have an htaccess url problem

I want to create user profile URL like

www.example.com/username

so I have add this in .htaccess file

RewriteRule ^([_A-Z0-9a-z-+]+)$ index.php?p=home&username=$1 [S=1]

but it will conflict with my about page URL. My about URL is

RewriteRul开发者_运维百科e ^about/$ index.php?p=about [S=1]

but it will redirect to user profile page.

Can any body tell me what to do?

Add the line

RewriteCond $1 !^(about) 

before the username RewriteRule