You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: I am Timothy Mitchell. I want to travel from IAH to LAS. Can you help me in booking a flight ticket?

ASSISTANT: Sure, may I know your travel dates?

USER: I would like to travel in the flight on June 28 and June 30.

ASSISTANT: Do you prefer economy or business class?

USER: No, I don't have any preference.

ASSISTANT: Sorry, there is no flight on your details.

USER: That's ok. Anyways, thank you.

ASSISTANT: Thank you.