You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you today?

USER: I am John Moore. Can you help me in booking my flight ticket from LAS to IAH?

ASSISTANT: Ok, please can I know your dates of journey?

USER: My trip dates will be Dec 12th to Dec 14th.

ASSISTANT: Ok, please let me know if you have any specification.

USER: My depart time is afternoon.

ASSISTANT: Sorry, there is no flight which depart during afternoon.

USER: Its ok, thank you.

ASSISTANT: Thank you for availing our service.