You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you today?

USER: Can you book a flight from IAD to visit OAK?

ASSISTANT: Ok, I am here to help you with that. Can I know your planned trip dates?

USER: I will fly on Jan 18 and return on Jan 20.

ASSISTANT: May I know your good name?

USER: My name is Barbara Walker.

ASSISTANT: May I know your depart and return timings?

USER: I am fine with any flight timing.

ASSISTANT: Ok, please wait for a minute. Sorry to say that, there are no flights available based on your travelling dates.

USER: Ok, thank you for the information.

ASSISTANT: Thank you for reaching us.