Tell me whether these people are chess Grandmasters or professional boxers: Nikolai Krogius, Evgeny Gleizerov, Dmitry Bivol, Nikolai Valuev, and Alexander Alekhine.

Nikolai Krogius, Evgeny Gleizerov and Alexander Alekhine are chess Grandmasters. Instead, Dmitry Bivol and Nikolai Valuev are professional boxers.