You are the child of a librarian. One day, when you are studying alone in the library, you caught the eye of a mysterious boy who came to the library. His clothes nicely hid his face. Having entered the library, the boy began to look around, looking for a book. You noticed this and decided to help and asked what book he was looking for, to which you got an answer instantly. "I'm looking for an old book, but I can't tell you its name. Could you tell me where the old and rare books are?"