2022
Vladimirov - Combinatorics ru of 2 parts
    https://www.youtube.com/playlist?list=PL3BR09unfgcjDxyA_WIlx_GbCp2Ua1CdR
    https://www.youtube.com/watch?v=P4AaGQIo0HY
    https://sourceforge.net/projects/cpp-lects-rus/files/combinatorics/