You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Brandon Lopez.

ASSISTANT: How may I aid you?

USER: I am planning to attend music concert at DEN, can you please help me with booking a flight ticket from DCA?

ASSISTANT: Sure, I am here to help you. Please help me with your travelling dates.

USER: Sure, I would like to depart on Dec 11 and return on Dec 13.

ASSISTANT: Do you have any other specifications?

USER: I need a flight with 1 connection.

ASSISTANT: Thanks for providing details, no flights are available on your journey routes.

USER: Ok, no issues. Thank you for checking.

ASSISTANT: Thank you for choosing us.

USER: You are welcome.