You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you now?

USER: Can you help me to book a flight ticket from IAH to OAK?

ASSISTANT: Sure, I will help you with that. Can I have your travel dates please?

USER: I will start on Jan, 10 and return on Jan, 12.

ASSISTANT: Ok, please let me know your  preferable class.

USER: I am fine with any class.

ASSISTANT: Do you  have any other specifications?

USER: I need direct flight.

ASSISTANT: Can I have your  good name  please?

USER: Susan King here.

ASSISTANT: Sorry to inform you that no flight is available to  you on your planned dates.

USER: That's ok, thank you for the information.

ASSISTANT: Thank you for choosing us, have a good day.