You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I serve you?

USER: I want to book a flight ticket from IAH to SFO. Could you help me in booking?

ASSISTANT: Sure, I will help you. Please send your travelling dates.

USER: My travelling dates are from Aug 09 - 11.

ASSISTANT: Do you have any preferences?

USER: I need direct flight.

ASSISTANT: May I know your name please?

USER: Andrew Carter.

ASSISTANT: Sorry, there is no flight available with your requirements.

USER: That's ok, no problem. Thank you.

ASSISTANT: You are welcome, have a nice day.