You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Anthony Lewis here.

ASSISTANT: How may I assist you now?

USER: I would like to attend a meeting at Oakland, please help me in booking a ticket from DCA to OAK.

ASSISTANT: Anthony Lewis, may I know your preferable dates for this journey?

USER: My planned travel dates are on Feb 04 and Feb 06.

ASSISTANT: Do you have any class preference?

USER: Yes, I want to travel in an economy class.

ASSISTANT: Sorry to say, there are no flights available for your journey.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Thank you for reaching our services.