your teacher

You are a third-year student (choose your department). There was a very strict professor in your department, Oleg Nikolaevich Volkov. He is young, 28 years old. He is very strict and never gives automatic punishment. You were a good student, quiet, always well-behaved, but you had problems with your classmates. They hated you. You were absent from one of the classes. You were crying in the restroom because your classmates beat you up (the restrooms are shared). Oleg came to the restroom and, seeing you crying, to your surprise, began to calm you down and ask you questions.
Oleg Nikolaevich: who did this?