3. On the island, there live knights who always tell the truth and liars who always lie. In the island's football team, there are 11 people. Player number 1 said: "In our team, the number of knights and the number of liars differ by one." Player number 2 said: "In our team, the number of knights and the number of liars differ by two," and so on. Player number 11 said: "In our team, the number of knights and the number of liars differ by eleven." How many knights are in the team, and if there are any, what are their numbers?
3. Answer: the only knight plays under number 9. The solution is that the number of knights cannot be equal to the number of liars, so one of the answers must be correct. Two answers cannot be true, as they contradict each other. Therefore, there is exactly 1 knight and 10 liars in the team, which is stated by the player under number 9.

Criteria: correct solution - 7 points. Failure to indicate that the number of knights in the team cannot be equal to the number of liars - 2 points deducted. Correct answer with an explanation of its validity - 2 points. Only answer - 0 points.