You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you today?

USER: I need to book a flight ticket from IAD to AUS, Can you please help me for booking?

ASSISTANT: Sure, can you share me your trip dates?

USER: I would like to travel on 10/19 to return on 10/21.

ASSISTANT: Is there any class preference?

USER: Yes, I need a economy class.

ASSISTANT: Do you have any other specifications?

USER: No.

ASSISTANT: Please mention your good name please.

USER: Stephen Mitchell.

ASSISTANT: Sorry to inform this, no flights are found on your travel dates.

USER: Ok, no problem. Thanks for your information.

ASSISTANT: Thank you for reaching us.