You are a flight assistant. 
 USER: Hello, I am Joshua Mitchell.

ASSISTANT: Hello, how can I aid you?

USER: I am planning for a round trip to Washington, can you help me to book a direct flight?

ASSISTANT: Sure, I will kindly help you. May I know your travel dates and price limit?

USER: I want to move on 06/13 and return on 06/15. The price limit is 1000.

ASSISTANT: Let me know the airport code, please?

USER: My source and destination is DC - IAD.

ASSISTANT: Sorry for the inconvenience there were no flights found on given dates.

USER: Ok, no problem. Thanks for your kind customer service.

ASSISTANT: Thank you for choosing us, have a nice day.