This trick is well known in China.
For poor people that cannot use youtube:
https://www.bilibili.com/video/BV1uT4y1P7CX/
For international users:
For poor people that cannot use youtube:
https://www.bilibili.com/video/BV1uT4y1P7CX/
For international users:
Hereinafter assume div 1 notation is used.
Problem ?1: insignificant
Problem ?2: nonsense
Problem @: silly
Problem A: trivial
Problem B: dumb
Problem C: uninteresting
Problem D: stupid
Problem E: toxic
Problem F: not read
also bump when release editorial