You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you today?

USER: I am looking to book a flight ticket from DEN to DCA. can you help me for that?

ASSISTANT: Sure, can you please provide your journey dates?

USER: My travelling dates are Dec 03 and Dec 05.

ASSISTANT: Do you have any specifications to be met?

USER: My class preference is business.

ASSISTANT: May I know your name?

USER: My name is Sarah Miller.

ASSISTANT: Ok, please wait.

USER: Sure, I will wait for your response.

ASSISTANT: Thank you for your valuable time, unfortunately no flights available on that route.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for opting us.