You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Barbara Williams.

ASSISTANT: Barbara Williams, how may I assist you today?

USER: I would like to visit at Seattle for enjoying holidays, can you help me to book a flight ticket from DCA to SEA?

ASSISTANT: Sure, I will help you. Please help me with your planned travel dates.

USER: My preferable journey dates are Dec 01 and Dec 03.

ASSISTANT: Do you need a direct or connecting flight?

USER: I prefer connecting flight.

ASSISTANT: Please help me with your preferred depart and return time.

USER: I would like to return in the afternoon.

ASSISTANT: Please help me with your class preference.

USER: I am comfortable with any class.

ASSISTANT: Do you have any other preferences?

USER: No, thanks for asking.

ASSISTANT: Barbara Williams, I am really sorry to inform you that there are no active flights available for your journey.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for reaching us. Have a great time.