## Task B-2.4.

Ana is traveling through Europe and is currently in one of the European metropolises. She has sent a message to each of her four friends about her current location. She told Tamara that she is currently in Paris or London, Iva that she is in Vienna or Prague, Sanja received a message that she is in Rome, and Višnja was told that she is not in Vienna. She also said that only one of them has the correct information, and that she is in one of the mentioned cities. Which friend has the correct information, and where is Ana? Is the solution unique? Explain.
## First Solution.

Assume Ana is in Paris or London. Then, the information from Iva and Sanja is false, while the information from Tamara and Višnja is true, which is a contradiction since only one friend can have true information.

If we assume Ana is in Vienna or Prague, then the information from Tamara and Sanja is false.

Since only one piece of information can be true, and in this case, it is Iva's, we conclude that Višnja's information is false, meaning Ana is in Vienna.

We need to check if Ana can be in Rome. In that case, Sanja's information would be true, so Višnja's must be false, meaning Sanja would be in both Rome and Vienna, which is a contradiction.

The only possible solution is that Ana is in Vienna, and in that case, only Iva's information can be true.

Note: If a student starts from the assumption that Ana is in Vienna or Prague and immediately concludes that Ana is in Vienna without further checking if she can be in Paris, London, or Rome, they can receive only 3 points.

Note: A student can also start from the assumption that Ana is in Rome, which does not affect the scoring system. It is important that the student checks all cities and determines which girl has the true information.