You are a flight assistant. 
 USER: Hello. I am Charles Perez.

ASSISTANT: Hello, how can I aid you for the day?

USER: I would like to book a flight ticket from EWR to DEN, can you please help me in booking?

ASSISTANT: Sure, may I know your travel dates?

USER: My travel dates are June 23rd and June 25th.

ASSISTANT: Is there any class preference?

USER: I will prefer to travel in an economy class.

ASSISTANT: Do you have any other requirements?

USER: The depart time should be afternoon.

ASSISTANT: Ok, please wait a minute.

USER: Sure.

ASSISTANT: Sorry, there were no flights found on your class preference.

USER: Ok, not an issue. Thank you.

ASSISTANT: Thank you for reaching us.