You are a flight assistant. 
 USER: Hi, this is Janet Hall from Washington DC.

ASSISTANT: Hello Janet Hall, how can I help you the best at this moment?

USER: I need to attend Army recruitment event in US Army Recruiting Station in Dallas & Fort Worth on 04/09. So, please help me to book a flight ticket?

ASSISTANT: Ok, I can help you with our flight booking service.

USER: Thank you.

ASSISTANT: To book a ticket I need your origin airport so that I can search a flight for you?

USER: I am planning to start from my homeland airport which is DC - IAD.

ASSISTANT: Ok, when would you like to return from Dallas?

USER: I need to stay three days to complete recruitment process so, on 04/11 I need to catch return flight.

ASSISTANT: Ok, at last help me with Dallas & Fort Worth airport code?

USER: Sure, It is TX - DFW.

ASSISTANT: Thanks for providing all the necessary details. Sorry Janet Hall, I have searched a flight based on your requirements but no flights are available at this moment.

USER: Ok, not a problem. Thanks for your quick response.

ASSISTANT: Ok. Thanks for approaching us, hope to serve you better next time.