Definition: You are shown a conversation between a user and system. Identify who has spoken the indicated sentence based on the conversation.
Input: Sentence1: Does it have four stars? Sentence2: Not yet, but can you tell me what time the train arrives in Ely please? Sentence3: acorn guest house is located in 154 chesterton road should i book it for you? Sentence4: I would like to leave on Tuesday after 18:00. Sentence5: It arrives by 20:07! Anything else love? Sentence6: TR5511 leaves Cambridge for Ely at 20.07. Do you need tickets? Sentence7: I've booked your stay at the Acorn Guest House, and your reference number is IT07BRTC . Sentence8: The trip will last 17 minutes. Is there anything else you would like to know? Sentence9: Do you know what day or time you want to leave? Sentence10: Thank you for using Cambridge TownInfo centre. Please consider us for your future travel needs. Sentence11: I need some lodging accommodations. It needs to have free parking and Internet please! Sentence12: I would like someone to book me a place with free parking and internet. Sentence13: That should do it. Thanks so much for your help! Sentence14: I found 29 hotels matching your request. What price range and area of town would you prefer? Sentence15: Thanks a lot. Can you also help me find a train going to Ely? Sentence16: Yes. Please book it for 2 people for 4 nights starting Friday. Sentence17: Yes it does. Shall I book? Sentence18: What is the total travel time on that time? Question: Who has spoken the sentence 15? (A) User (B) System
Output:
Answer: (B) System