How to number pages in pdf document? How can I add numbers to pages in pdf document? 

Is there a free software for this?

I found in google only full version of Adobe Acrobat, which can make it.

This works, but I need to add number in right corner for each odd page and in left corner for each even page.
You can use Preview. Tools Menu/Annotate/Text, or it's the top right icon next to the search box, then icons appear below for annotation choices.