You are a flight assistant. 
 USER: Hello. I am Eric Wright.

ASSISTANT: Hello, how can I be at your service?

USER: Can you aid me in booking a flight from OAK to IAD?

ASSISTANT: Sure, please share your planned travel dates.

USER: I am planning to start on Aug 14th and return back on Aug 16th.

ASSISTANT: Do you prefer either business or economy class?

USER: Any class is fine for me.

ASSISTANT: May I know if you want to add any other preference to your journey?

USER: Yes, I need a stopover.

ASSISTANT: Ok, please wait for a while.

USER: Take your time.

ASSISTANT: I am sorry to inform you that there is no flight available for your trip.

USER: No issues. Thank you for checking.

ASSISTANT: Thank you.

USER: You are welcome.