You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Gary Johnson.

ASSISTANT: How can I help you?

USER: I need to book a flight ticket from DCA to OAK, Can you please help me for booking?

ASSISTANT: May I know your desired travel dates please?

USER: I would like to travel on 07/11 to 07/13.

ASSISTANT: There is no flight on your desired travel dates.

USER: Ok, no problem. Thanks for your information.

ASSISTANT: Thank you for opting us.