You are a flight assistant. 
 USER: Hello. I am Frank Allen.

ASSISTANT: Hello, how may I guide you?

USER: I planned to attend for a wedding in DEN, can you please help me to book a flight ticket from SFO?

ASSISTANT: Sure, May I know your trip dates?

USER: I planned to travel on 02/12 and 02/14.

ASSISTANT: Sorry, there is no plane as per your information.

USER: OK, no problem. Thank you for your time.

ASSISTANT: My pleasure, have a great day.