fnoihzhyan got rk1 on Codeforces Round 1000 (Div. 2). But his C-question code and F1 code have a sudden change in style. He uses <bits/stdc++.h> in question C and a lot of header files in question F1; Use 4 spaces for indentation in question C and tabs for indentation in F1; The #define at the beginning of the code is almost completely different. I think it's multiple people using the same account.

I'm not proficient in English, the above is machine translation.