adobe acrobat pro

I really like Adobe Acrobat Pro, but it’s way too expensive for me. I really enjoyed the trial version. I made a really good study guide with this program. Is there any other program I can use for free to edit PDF files? I want to be able to EDIT them, not just read them. And by editing I mean adding and deleting pages, make one PDF file out of multiple PDF files, edit the page numbers etc.

I love this program so much, please help me! :)