LDAP Filter - Two OU same O

Gentlemen, help me please!

I do not have much knowledge with LDAP filters.

I’m trying to integrate Openfire with LDAP.

My DN is as follows:

domain.com

-> O=users

------> OU=group_1

------> OU=group_2

------> OU=group_3

Within each group have the users (uid).

I need a filter that only bring OU=group_1 and OU=group_3.

**- What is syntax? **

- And where do I put this filter there in Openfire?

Thanx!

Luciano Zeni