You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am Angela Taylor. I am looking for a direct flight to Washington, could you please help me with booking a flight ticket?

ASSISTANT: Sure, please tell me your preferable travelling dates.

USER: I would like to take off on 12/06 and return on 12/08.

ASSISTANT: Ok, please tell me your airport codes.

USER: My nearest source airport code is SFO and destination airport code is IAD.

ASSISTANT: Angela, all flight tickets are sold out in your requested travel dates.

USER: That's ok, I will find an another alternate way to complete my trip. Anyways, thank you for the information.

ASSISTANT: Thank you for consulting us, have a great day.