You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: I am Debra Thompson. I want to book a flight ticket from OAK to PHL. Could you help me in booking?

ASSISTANT: May I know your travel dates?

USER: My travelling dates are from 12/20 to 12/22.

ASSISTANT: Sorry for this inconvenience, I could not find any flight with your requirements.

USER: That's ok, no problem. Thank you.

ASSISTANT: Thank you for reaching us.