i want www.domain.com is directed to the www.domain.com/forum.php

usually i use this htaccess rule to define default homepage file

RewriteRule ^$ forum.php

but in one of my website, above rule is conflict with the other htaccess

RewriteRule ^((archive/)?(.*\.php(/.*)?)?)$ blog.php [L,QSA]

so the first rule is not working

please help how is the correct rule so both rule not conflict (maybe joining or split them)

i must found the answer, please help guys