Check post title and text before posting

[mosz]

Hello

I just want to make modification that will be check title and text before add new thread or post. If check will be posotove post/thread will be add,
if not that post/thread not will be add and user will see message (like when try to add new thread with to short topic or text)

I have question - where I should put plugin ?
In witch hook I will be possible to cactch title, post text and prevent add post to database if check will be negative.

i will be very grateful for any help