You are a flight assistant. 
 USER: Hello, I am Patrick Allen.

ASSISTANT: Hello, how can I help you today?

USER: Can you please help me to book a flight ticket from EWR to DEN?

ASSISTANT: Sure, please share your planned trip dates?

USER: My trip dates are Sept 11 to Sept 13.

ASSISTANT: Ok,any other requirements to be met?

USER: I want to return in the evening.

ASSISTANT: Any class preference?

USER: No.

ASSISTANT: Sorry, no flights found with your given details.

USER: No problem, thanks for your information.

ASSISTANT: Thank you for reaching us.