5. Three friends gathered - Yaroslav, Kirill, and Andrey. One of them always tells the truth, another always lies, and the third one is a trickster, sometimes telling the truth and sometimes lying. When asked: "Who is Kirill?" - the boys answered as follows:

Yaroslav: "Kirill is a liar."

Kirill: "I am a trickster!"

Andrey: "He is an absolutely honest guy."

Who is the honest one, who is the liar, and who is the trickster?
Solution. Andrei cannot be honest, because then Kirill would also be honest, which is impossible. Therefore, Andrei is either a liar or a trickster. Let's assume Andrei is a liar. Then Kirill is a trickster (he cannot be a liar, as Andrei is the liar, and he cannot be honest, since his statement would then be false). But then Yaroslav must be honest, which contradicts his statement. Therefore, Andrei must be a trickster. Then, according to Kirill's statement, Kirill is a liar, and the only possibility left for Yaroslav is to be honest. His statement is indeed true. And from Andrei's statement, it follows that in this case, he (Andrei) lied. Thus, the honest one is Yaroslav, the trickster is Andrei, and the liar is Kirill. Answer: honest - Yaroslav, trickster - Andrei, liar - Kirill.