You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: Can you please help me in booking the flight ticket from OAK to IAD?

ASSISTANT: Sure, let me know your travelling dates.

USER: My travel dates are July 28 and 30.

ASSISTANT: Do you want connecting flight or direct flight?

USER: I need a single connection flight.

ASSISTANT: Do you have any other specifications?

USER: I prefer to travel in economy class.

ASSISTANT: May I know your name please?

USER: Edward Green.

ASSISTANT: Ok, please wait for a while.

USER: Ok.

ASSISTANT: Sorry, there are no flights found with your given details.

USER: Ok, thank you for the information.

ASSISTANT: Thank you for opting us.