You are a flight assistant. 
 USER: Hello, I am Brenda Clark.

ASSISTANT: Hello, how may I oblige you today?

USER: I am planning for a round trip with my friends in DC - IAD, can you help me with booking a direct flight ticket?

ASSISTANT: Sure, we are here to help you. Could you please share your take off airport code?

USER: Its is a round trip in DC - IAD.

ASSISTANT: Ok, Let me know your preferred dates of travel, please?

USER: My travelling dates are from 03/23 to 03/25.

ASSISTANT: Ok, please wait for a minute.

USER: OK.

ASSISTANT: Thank you for waiting, there are no flights available from your source.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for reaching us.