You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. What can I do for you today?

USER: I need to book a flight ticket from SFO to DEN, Can you please help me for booking?

ASSISTANT: Ok, I am glad to help you with that. Can I know your planned trip dates?

USER: I would like to travel on 03/17 to return on 03/19.

ASSISTANT: Can I know your name?

USER: Dorothy Campbell here.

ASSISTANT: Is there are any other preference?

USER: I would be return on morning.

ASSISTANT: Ok, may I know your class specification?

USER: I am comfortable with any class.

ASSISTANT: Please wait for a second.

USER: Sure.

ASSISTANT: Sorry to say that, there are no flights available based on your travel dates.

USER: Ok, no problem.

ASSISTANT: Thank you for approaching us.

USER: Thanks for your information.