You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you today?

USER: I want to travel from IAD to OAK. Can you help me to book a flight ticket?

ASSISTANT: Sure, I will help you with that. Can you please share your preferable travel dates?

USER: I want to fly in the flight on Apr 22 and Apr 24.

ASSISTANT: May I know your name please?

USER: David Carter.

ASSISTANT: Do you have any class preference?

USER: I prefer to travel in economy class.

ASSISTANT: Would you like to board a connecting flight or  direct flight?

USER: I am looking for a connecting flight.

ASSISTANT: Do you have any other specifications?

USER: I want to return in afternoon time.

ASSISTANT: There are no flights available on this route as per your travel dates.

USER: That's ok. Anyways, thank you.

ASSISTANT: Thank you for reaching us, have a great day.