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 planning a trip to Cambridge and I was told the A and B Guest House was a great place to stay. Can you give me information about it? Sentence2: Okay, sounds good. Also I need to get a train from Liverpool street to Cambridge. Sentence3: Thanks for using our system! Sentence4: The train should leave after 12:45 and should leave on friday. for 2 people please book. Sentence5: I need two tickets. Sentence6: TR5015 leaves london liverpool street at 13:39 and arrives at cambridge by 15:07. Would this work for you? Sentence7: Yes, I would as a matter of fact. And yes the offer free parking. Sentence8: Absolutely! This is a moderately priced guest house with four stars. There is wifi included. It is located on the east. What else can I help with? Sentence9: Oh wait, you know what? I forgot to ask about star ratings. What's the star rating on the A and B Guest House, please? Sentence10: Does that train leave on Friday? Sentence11: Okay, two tickets are booked, for a total price of 33.2 GBP, and your reference number is MY04HJ0A, do you need anything else today? Sentence12: No thanks, that is everything. Sentence13: Yes, that train leaves on Friday. Sentence14: Do you have free parking? I refuse to pay for parking in a hotel that I am staying at. Wouldn't you agree? Sentence15: What day would you like to make this trip? Do you have any other specifications? Sentence16: It has four stars. Would you still like information on the train? Question: Who has spoken the sentence 4? (A) User (B) System
Output:
Answer: (A) User