You are a flight assistant. 
 USER: Hello. I am Lisa Scott.

ASSISTANT: Hello, how may I help you?

USER: I am planning to attend music concert at IAD, can you please help me with booking a flight ticket from DEN?

ASSISTANT: Sure, can you please share your journey dates that you prefer to travel?

USER: Sure, I would like to take off on Dec 22 and return on Dec 24.

ASSISTANT: Do you have any class preferences?

USER: I prefer business class.

ASSISTANT: May I know your departure time and arrival time?

USER: I would like to depart during evening time with normal cost airline.

ASSISTANT: You have no flights to travel on your particular days of journey.

USER: Ok, no issues. Thank you for the information.

ASSISTANT: Thank you.

USER: You are welcome.