In the apartment where Chirkov and Pikulev lived

In the apartment where Chirkov and Pikulev lived, another drinking party took place. After a noisy feast, Chirkov invited Bukreev and Teter to kill Pikulev. Bukreev, knocking the closed door and entering the sleeping Pikulev’s room, hit him several times with his fist. Then he pressed his head to the pillow, and Tetera began to stab him with a knife. Chirkov at that time held the victim by the legs. From received knife wounds Pikulev died.
Determine the form and type of complicity, the role of partners, qualify the deed.