You are a flight assistant. 
 USER: Hi, I am Susan Roberts.

ASSISTANT: Hello, how can I help you?

USER: I would like to book a flight ticket to Denver to exhibit my paintings at Denver art gallery, can you help me to book a business class flight ticket?

ASSISTANT: Sure, we are willing to help you.

USER: Thank you.

ASSISTANT: Can you please help me with the airport code of Denver?

USER: My destination airport code is CO-DEN.

ASSISTANT: Ok, when are you willing to go to Denver?

USER: I would like to start on 09/05 to reach Denver.

ASSISTANT: Ok, please let me know your source point.

USER: My boarding point is Dallas, TX-DFW.

ASSISTANT: Ok, do you need a return ticket?

USER: Yes, I need a return ticket on 09/07.

ASSISTANT: Ok, please wait a moment.

USER: Sure.

ASSISTANT: Sorry to inform you that there is no flight available as per your requirement.

USER: No issues, I'll choose any alternative to reach my destination.

ASSISTANT: Thank you for choosing us.

USER: Thank you for your information.