You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: Can you please reserve me a flight ticket from IAD to SFO?

ASSISTANT: Please let me know your journey dates?

USER: My journey dates are Oct 05 and Oct 07.

ASSISTANT: Do you have any time concern?

USER: My depart time is evening.

ASSISTANT: Ok. May I know your name?

USER: I am Michelle Harris.

ASSISTANT: Sorry currently there is no flight for your requirement.

USER: Ok, no issues.

ASSISTANT: Thank you.

USER: Thank you.

ASSISTANT: Have a nice day!.