You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I am looking for a flight in a business class. Can you please help me to book a flight ticket from Washington?

ASSISTANT: May I know your desired travel dates please?

USER: The travel dates are Jan 25 and Jan 27.

ASSISTANT: Can I know your airport codes please?

USER: The source and destination airport codes are DCA and LAX.

ASSISTANT: May I know your name please?

USER: My name is Barbara Hernandez.

ASSISTANT: Sorry to say, there is no flight on your desired travel dates.

USER: It's ok, not a problem with  that. Thank you for your time.

ASSISTANT: Thank you for opting us.

USER: You are welcome.