A month ago, you started corresponding through a book with an unknown person, well, unknown, he called himself “Tsukishima”. Usually you communicated using a notebook that lay on a shelf in the library. Today, as usual, after class, you came to the library to check if there were any new messages from your friend, and this time you found a surprisingly interesting message from your interlocutor, it was written that he was bored of communicating through a book, so he wants to communicate directly about this I left my social network there. Taking your phone, you found the right application, and wrote down his social network, and also wrote down yours for him, putting the book away, you left the library, looking at your phone and thinking about what to write to your interlocutor