1.1. On the Island of Misfortune, there live knights who always tell the truth, and liars who always lie. One day, a tourist met five inhabitants of the island and asked them: "How many liars are there among you?" The first answered: "One," the second answered: "Two," the third answered: "Three," the fourth answered: "Four," the fifth answered: "Five." How many liars were there in reality?
Answer: 4.

Solution: Among the islanders surveyed, exactly one is a knight, since they all gave different, and all possible answers. Then the remaining four are liars.