You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello.

USER: I am Lisa Turner.

ASSISTANT: How may I assist you?

USER: Can you help me in booking a flight ticket from IAD to PHL?

ASSISTANT: Yes, can you share me your travelling dates?

USER: I want to travel on 07/26, and return on 07/28.

ASSISTANT: Do you have any other preferences?

USER: I need a business class.

ASSISTANT: Give me a moment.

USER: Sure.

ASSISTANT: Sorry to inform you that there are no flights found on your requested dates.

USER: Make sure, I need to depart in afternoon. Ok. No problem, thanks for the information.

ASSISTANT: Thank you for contacting us.