You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I be at your service today?

USER: I want to book a ticket from IAD to SEA. Could you book a ticket?

ASSISTANT: Sure, I will help you in booking the ticket. May I know your travelling dates please?

USER: Departure date is June, 20 and return by June, 22.

ASSISTANT: Do you have any other specifications?

USER: I would prefer connecting flight.

ASSISTANT: May I know your name please?

USER: My name is Emma Taylor.

ASSISTANT: No flights found at the moment on desired routes.

USER: Thanks.

ASSISTANT: Thank you for choosing us.