What ideas have you had so far?
I only remember general knownledge
This is not a homework service. You're expected to put forth some effort, at which point we can help you get unstuck. See Rule # 11 here.
I note that you've posted a lot of problems. That's perfectly fine. However, you need to post some effort in each one, and not expect us to simply solve them for you. That's not what this forum is about.