You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I need a direct flight, Could you please help me with booking a flight ticket?

ASSISTANT: Sure, please provide me your planned travel dates.

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

ASSISTANT: Do you prefer either economy or business class?

USER: I am comfortable with any class.

ASSISTANT: May I know your airport codes?

USER: Sure, my airport codes are IAH and LAS.

ASSISTANT: Do you have any other preference?

USER: Yes, I want to return in the evening.

ASSISTANT: Sure, may I know your name please?

USER: I am Jeffery King.

ASSISTANT: Sorry, we didn't find any flight for your journey criteria.

USER: No worries, thank you for the information.

ASSISTANT: Thank you.