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 want to leave on Friday. Sentence2: I am looking for a train that goes to london liverpool street and leaves after 17:15. Sentence3: Nope, that is everything. Thank you so much! Sentence4: Unfortunately, the only train I have matching your criteria is one leaving 23:59 and arriving at 01:27 in the morning. Did you want to book that? Sentence5: Yes that's fine. I'll take 8 tickets for that train please. Sentence6: Alright, your train tickets have been booked and the reference number is NFA1DPXI . The train ID is TR3138. Is there anything else I can help you with? Sentence7: I can certainly help you with that. Which day did you have in mind to travel? Sentence8: Have a great day! Question: Who has spoken the sentence 5? (A) User (B) System
Output:
Answer: (B) System