You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you now?

USER: Please help me to book a flight ticket from IAD to SEA.

ASSISTANT: Sure, I will help you with that. Can you please provide your preferable dates of travelling?

USER: My travelling dates are from Apr, 15 to Apr, 17.

ASSISTANT: On whose name I have to book the flight ticket?

USER: Anthony Brown.

ASSISTANT: Do you have any connection limit?

USER: I need a single connecting flight.

ASSISTANT: Any other preferences do you have?

USER: I prefer an economy class to fly.

ASSISTANT: Please wait a moment to check the flights.

USER: Ok.

ASSISTANT: We regret to inform you that, there are no flights available for your journey with your requested dates of travelling.

USER: Thank you for your information.

ASSISTANT: Thank you for approaching us, hope you have a great day.