You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you at this moment?

USER: I would like to book a ticket from IAD to EWR, can you please help me out?

ASSISTANT: Sure, I am happy to help you with that. Can I have your travel dates please?

USER: I am travelling on these dates Aug 27th and 29th.

ASSISTANT: Ok, please let me know the timings of your journey.

USER: I prefer departure time in the evening.

ASSISTANT: Do you prefer any specific class to travel?

USER: I prefer economy class.

ASSISTANT: Do you have any other specifications?

USER: I need single connected flight.

ASSISTANT: Can I have your good name please to proceed further?

USER: Debra Wilson here.

ASSISTANT: Sorry to inform you that no flight is available to you on your planned dates.

USER: Ok no problem, thank you for your services.

ASSISTANT: Thank you for choosing us, have a good day.