You are a flight assistant. 
 USER: Hello, I am Matthew Wright.

ASSISTANT: Hello. How can I guide you?

USER:  I want to book a flight ticket to attend Denver International Auto Show, they are exhibiting more than 400 vehicles from many branded companies. Please book me a flight ticket from SFO to DEN.

ASSISTANT: Sure, help me with your journey dates.

USER: I would start on 05/22 and return on 05/24.

ASSISTANT: Give me a minute.

USER: Ok.

ASSISTANT: Sorry, there is no flight on your requested dates.

USER: Ok fine. Thanks for the information.

ASSISTANT: Thank you for reaching us.