You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you today?

USER: Can you please book a ticket from LAS to HOU?

ASSISTANT: Sure, may I know your travel dates?

USER: My travelling dates are May 17 and May 19.

ASSISTANT: Do you have any specifications?

USER: My return time is afternoon.

ASSISTANT: Please share me your name.

USER: I am Nicholas Rodriguez.

ASSISTANT: Sorry, there is no flight at this moment.

USER: Ok, Thank you for your help.

ASSISTANT: Thank you.