Hi everyone,

A few months ago, I participated in a contest and encountered a geometry problem that has been stuck in my head ever since. I have tried searching for the official editorial or any existing solutions, but I couldn't find any.

Could you please provide some hints, a full solution, or even approaches for the subtasks? Since my English is not very good, I'm afraid that re-explaining the problem myself might lead to misunderstandings or incorrect terminology. Therefore, I have included the original problem link here for accuracy: problem here

Thank you very much for your help!