I couldn't solve this problem , so when I looked into its editorial I got to learn about the Goldbach's conjecture . It is fascinating for me, because this has not been proven formally yet, but somebody created an interesting problem with this.

Have you encountered any such conjecture in the problem set, if Yes, please share the conjecture and the problem. And also, if you were able to solve such problem on your own, what did you do ( I mean did you follow some intuitions, or searched for some related concepts)

Thank you !!