regex - htaccess - combine rewrites into single -

i have couple of rewriterules i'd combine one. i'm not sure how it, though. think arounds need used? difference between 2 first match like:

search/foo or search/foo/

and second match

search/foo/10 or search/foo/10/

rewrites:

rewriterule ^search/([a-za-z]+)/?$ index.php?page=search&query=$1&pn=1 [l] rewriterule ^search/([a-za-z]+)/([0-9]+)/?$ index.php?page=search&query=$1&pn=$2 [l] 

without using arounds, attempt

^search/([a-za-z]+)/?([0-9]+)?/?$

but think match undesirable this?

search/foo10

edit:

i'm tryin regex match following uris:

1. search/foo
2. search/foo/
3. search/foo/1
4. search/foo/1/

^search/([a-za-z]+)(/)?([0-9]+)?\/?$  

will work? might have make '/' match pattern , ignore $2.same can followed trailing '/' , ignore $4.