upd: has been fixed now
This seems like a problem. On problem A, the statement guarantees $$$2 \leq n \leq 10^{14}$$$, but the validator accepts $$$n = 1$$$, causing an invalid edge case for many solutions.
For example, this hack should not work. The input is just:
1
1
pinging {Supermagzzz, Stepavly, MikeMirzayanov}
It should be fixed, but the round is already unrated so IMO it doesn't affect much.
This doesn't affect the point of this blog, but as a side note, it seems strange that the statement doesn't allow $$$n = 1$$$ in the first place.
It's a big mistake, I'll wix it. Thanks for the issue.