You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Jerry Martin from Los Angeles.

ASSISTANT: How may I assist you at this moment?

USER: Can you please book a flight ticket from LAX to DCA?

ASSISTANT: Sure, I am here to help you. Can I have your planned trip dates?

USER: Sure, I need to travel on dates of 05/18 and 05/20.

ASSISTANT: Ok, please wait for minute.

USER: Sure, take your time.

ASSISTANT: Sorry to say that, there are no flight's available based on your travelling dates.

USER: Oh! It is sad to hear. Anyway, thank you for your time.

ASSISTANT: Thank you for opting us.

USER: Most welcome.