You will be given a definition of a task first, then some input of the task.
You are shown a conversation between a user and system. Identify who has spoken the indicated sentence based on the conversation.

Sentence1: I'm looking for a 0 star guesthouse in the north. Sentence2: We have 23 museums in Cambridge. Could you help me narrow down your search with an area or price range? Sentence3: Sure. Have a nice day. Sentence4: There is the City Centre North B and B. Would you like me to book this for you? Sentence5: You as well! Goodbye! Sentence6: Unfortunately, I don't have any guesthouses that are in the expensive range. Is there any other price range you would consider? Sentence7: Yes. I can go ahead and book that for you if you can give me the the days you'd like to stay. Sentence8: Unfortunately I was not able to book that time slot for you. is there another day you would like to try? Sentence9: Sure, Cambridge Artworks Museum is on Greens Road, post code cb13ef. Is there anything I else I can help you with today? Sentence10: Great! Thanks for using our service. Sentence11: How about one in the cheap price range? Sentence12: Howdy! I'd like to go to a museum. Sentence13: Okay, I was able to book you for 2 nights with 8 people at City Centre North B and B. Your reference number is NXW9XX08 . Is there anything else? Sentence14: Can you recommend an expensive guesthouse? Sentence15: Is that in the cheap price range? Sentence16: Can I book for 8 people for 3 nights starting Tuesday? Sentence17: Could you recommend one to me? I am not looking for one in particular. May i also have it's postcode? Sentence18: I believe that's your job, right? Could you book it for me? Sentence19: Looks like there's some confusion. I need the hotel on Tuesday, for 3 nights, and 8 people. If that doesn't work, try 2 nights instead. Sentence20: There are no zero star places in that area, can I checked another area for you or another star rating place? Sentence21: Thank you. No, that will be all. Sentence22: If you could, that would be awesome. Question: Who has spoken the sentence 4? (A) User (B) System
Output:
Answer: (A) User