You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you?

USER: Can you aid me to book a flight ticket from IAD to PHL?

ASSISTANT: Please provide your journey dates.

USER: My trip dates are Apr 13 and Apr 15 respectively.

ASSISTANT: Do you need any connection limit?

USER: I want a connecting flight.

ASSISTANT: Do you need any other specifications?

USER: I choose economy class to travel.

ASSISTANT: May I know your name?

USER: Mark Davis here.

ASSISTANT: There are no flights available on your routes.

USER: Thank you.

ASSISTANT: Thank you for choosing us.