You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

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

ASSISTANT: May I know your desired travel dates please?

USER: I would like to take off on Apr 15 and return on 17.

ASSISTANT: Do you prefer direct flight or connecting flight?

USER: I prefer connecting flight.

ASSISTANT: Do you have any other specifications?

USER: Yes, I would like to return during evening time.

ASSISTANT: May I know your name please?

USER: My name is Jack Clark.

ASSISTANT: Sorry to say, there is no flight on your desired travel dates.

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

ASSISTANT: Thank you for opting us.

USER: You are welcome.