You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I serve you today?

USER: I want to book a flight ticket from DEN to DCA, can you please help me?

ASSISTANT: Sure, let me know your trip dates please?

USER: Thank you for your response, I planned my trip on the dates Sept 14 and Sept 16.

ASSISTANT: Is there any class preference?

USER: No, I am happy with any class.

ASSISTANT: Any other preference?

USER: Yes, I prefer morning flight at the time of depart and make sure to check with the connecting flight.

ASSISTANT: Can you share your name please?

USER: Myself Dennis Hernandez.

ASSISTANT: Sorry, no flights found as per your requirement.

USER: No issue, anyway thank you for checking.

ASSISTANT: Thank you for contacting us.