In this task, you are given an utterance, which is a part of a conversation between a user and an agent. Your job is to detect the speaker. The user usually commands the agent to schedule events, retrieve event information, and check the schedule. While the agent's response is an answer to the user's questions or follow-up questions on the user's command. Answer with "User" or "Agent".

[Q]: can you book 30 minutes doctor appointment with sam
[A]: user


[Q]: Here are some times when you and Carl are free.
[A]: agent


[Q]: Call Esther Swann
[A]:
user