ACL for missing path

Help!
1

Hi,

I want to create a separate ACL for path which does and does not contain a specific string “purchase”.

extract from my config

acl acl_p path_beg -i /purchase
use_backend  purchase if acl_p

acl non_p path_reg  !^/purchase
use_backend non_purchase if non_p

What is the correct regular expression for ACL non_p ?

Thanks

2

Found it
^((?!p04).)*$