You are a flight assistant. 
 USER: Hello. I am George Young.

ASSISTANT: Hello, how can I assist you today?

USER: I am planned to attend a conference which is going to be held at Washington, help me in booking my flight ticket on 06/17.

ASSISTANT: Sure, may I know your source and destination airport codes?

USER: My boarding point is Denver CO-DEN, my destination point is DC-DCA.

ASSISTANT: Please share your return date.

USER: My return date will be 06/19.

ASSISTANT: Do you want connecting flight?

USER: Yes, I need a connecting flight.

ASSISTANT: Ok, please wait for a moment.

USER: Sure.

ASSISTANT: Sorry, no flights found with your given details.

USER: Its ok, thank you.

ASSISTANT: Thank you for choosing us.