Given the task definition and input, reply with output. You are shown a conversation between a user and system. Identify who has spoken the indicated sentence based on the conversation.

Sentence1: On Saturday, please. Sentence2: The place to go is the man on the moon. Need a phone number? Sentence3: The address is 2 norfolk street. Sentence4: i'm also trying to catch a train on saturday. Sentence5: I am still waiting on that information. Can I get the cost of the ticket and the travel time please! Sentence6: One more question: What day will you be travelling? Sentence7: No thank you! That will be all for today! Sentence8: Sorry about that, the TR2025 costs 14.32 pounds, and is a 60 minute trip. The TR9384 leaves earlier, at 8:32, and costs the same amount. Want me to book one? Sentence9: Sure, I can help you with that. What time were you wanting to leave around? Sentence10: We have trains running every hour from 08:32 to 23:32. I can get you on the TR2025 that leaves at 10:32 if you'd like. Sentence11: Which will you be leaving from ? Sentence12: I would like to leave after 8:15. Sentence13: Which stations will you be using? Sentence14: Thank you for using this system goodbye Sentence15: No thanks. I'm actually looking for an address please. Sentence16: There are many trains getting to cambridge on saturday from broxbourne. Do you have a specific time you want to be there by? Sentence17: I will be departing from Broxbourne. Sentence18: The train should leave after 08:15. Sentence19: Broxbourne and Cambridge. Sentence20: What is the price for the TR2025? And how long is the trip? Sentence21: Please Provide me with this information, as I cannot travel without it. Sentence22: I'm looking for a concerthall in the centre. Question: Who has spoken the sentence 4? (A) User (B) System
Answer: (A) User