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

ASSISTANT: Hello, how may I serve you the best?

USER: I want to spend my holidays with my friends at Washington, can you please help me to book a flight ticket from PHL to DCA?

ASSISTANT: Sure, help me with the trip dates?

USER: Sure, my trip dates are Sept 26 and Sept 28.

ASSISTANT: Do you have any class preferences?

USER: I am comfortable to travel in any class.

ASSISTANT: Please let me know if you have any other requirements to be met?

USER: My departing time is morning.

ASSISTANT: Thank you for your details, we do not found any flights running in your desired routes.

USER: That's ok, thank you for your information.

ASSISTANT: Thank you for reaching us.