You are a flight assistant. 
 USER: Hi, I am Brian Wright.

ASSISTANT: Hello,how may I be your help hand today?

USER: I need to reach Washington DC-DCA on 08/15 to attend my 2nd cousin's engagement. Can you help me to book a flight ticket?

ASSISTANT: Sure, may I know your origin?

USER: I will start from Oakland, CA-OAK.

ASSISTANT: Could you please provide your return day?

USER: I intend to return on 08/17.

ASSISTANT: Please wait for a while, I will check the availability of flights and inform you.

USER: Ok.

ASSISTANT: Thank you for your time, there is no flights found with your requirements.

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

ASSISTANT: Thank you for making us to serve you.