Adsense ads depending on the post theme/topic(WordPress)

Hello. I know this must be possible but i dont know how to do this or what plugins do i need. I want to put adsense ads in my blog and to show something relevant to the post. For example if i make a post about flowers the ads just on that particular post to be about flowers. Can anyone help me? Thank you very much

 

ads depend on your post title and keyword used in post. noting need to do its auto