You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you?

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

ASSISTANT: Sure, We are here to help you.

USER: Thank you.

ASSISTANT: Can I know your travelling dates?

USER: My trip dates are May 25 and May 27.

ASSISTANT: Do you need any break?

USER: I am comfortable with any connection.

ASSISTANT: May I know your name?

USER: I am Patrick Lewis.

ASSISTANT: Is there any other specifications?

USER: No, thanks for asking.

ASSISTANT: Please wait a while.

USER: Sure.

ASSISTANT:  We are unable to provide flight in between your journey routes due to some technical up-gradation at destination airport.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for reaching us.