You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you?

USER: I need to book a ticket from IAD to JFK. Could you book a ticket?

ASSISTANT: May I know your trip dates?

USER: Departure is July, 28 and return date is July, 30.

ASSISTANT: May I know your connection limit preferences?

USER: I prefer connecting flight.

ASSISTANT: Do you have any other concern?

USER: I would like to depart in the evening time.

ASSISTANT: May I know your name please?

USER: My name is Sandra Taylor.

ASSISTANT: Sorry, no flights found as per your preferences.

USER: Thank you.