1. In the preliminary competition in which Nikola, Lazar, Vesna, and Sonja participated, to the question of what the order was, they answered:

Nikola: "Vesna is first, and Lazar is second"

Lazar: "Vesna is second, and Sonja is third"

Vesna: "Sonja is fourth, and Nikola is second"

Each of them gave one correct and one incorrect answer. What was the order?
Solution. If Lazar's statement "Vesna is second" is true, then both of Nikola's statements are false, which is not possible. Therefore, Vesna is not second, and Sonja is third. Then Vesna's statement "Nikola is second" is true. Since Nikola is second, Nikola's statement "Vesna is first" is true. According to this, the order was as follows: Vesna is first, Nikola is second, Sonja is third, and Lazar is fourth.