## 26.

So, let's start with a well-known problem. Three inhabitants of the island (A, B, and C) were talking to each other in the garden. A passerby asked A: "Are you a knight or a liar?" A answered, but so indistinctly that the passerby could not understand anything. Then the passerby asked B: "What did A say?" "A said that he is a liar," B replied. "Don't believe B! He is lying!" C interjected in the conversation.

Who among the islanders B and C is the knight and who is the liar?
26. Neither a knight nor a liar can say: "I am a liar" (by making such a statement, a knight would be lying, and a liar would be telling the truth). Therefore, A, whoever he was, could not have said that he was a liar. Thus, B, claiming that A called himself a liar, was definitely lying. This means B is a liar. And since C said that B was lying, and B indeed was lying, C spoke the truth. Therefore, C is a knight. Thus, B is a liar, and C is a knight. (It is not possible to determine who A was.)