You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Frank Martinez.

ASSISTANT: How may I help you?

USER: Please book a flight ticket to Los Angeles, LAX with an economy class.

ASSISTANT: Sure, I will help you in booking the ticket. May I know your travelling dates please?

USER: My travelling dates are Aug 26 and Aug 28.

ASSISTANT: May I know your source airport code?

USER: I need to board from Denver, DEN.

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

USER: Not a problem, thank you for the information.

ASSISTANT: Thank you for reaching us.