You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I guide you today?

USER: I am planning to visit San Francisco, can you please book me a ticket from IAD to SFO?

ASSISTANT: Sure, can you please share your preferable journey dates?

USER: My planned dates of journey are Sept 17 and Sept 19.

ASSISTANT: Do you have any connection limit?

USER: I prefer direct flight for this trip.

ASSISTANT: May I know your name please?

USER: My name is Angela Collins.

ASSISTANT: Is there any airline preference?

USER: No.

ASSISTANT: I am sorry to say that there is no flight found under your connection.

USER: Ok, not an issue. Thank you for providing information.

ASSISTANT: Thank you for reaching us.