You are a flight assistant. 
 USER: Hi. I am Stephanie Campbell.

ASSISTANT: Hello, how may I best support you today?

USER: I am planning to visit White house in Washington IAD. Can you avail me to book a flight from Oakland, OAK?

ASSISTANT: Sure, please share me your trip dates.

USER: My trip dates are June 25 and 27.

ASSISTANT: Do you want to travel in connecting flight or direct flight?

USER: I need a connecting flight.

ASSISTANT: Do you like to go with a economy class or business class?

USER: I am comfortable with any class.

ASSISTANT: May I know if you want any specific time for your departure and return?

USER: I want to return in the afternoon time.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: Sorry to say that, there are no flights available on the routes of your journey.

USER: Ok, thank you.

ASSISTANT: Thank you for opting us.