You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Dorothy Rodriguez.

ASSISTANT: Dorothy, how can I aid you today?

USER: I want to attend a business meeting at DEN, can you please book me a ticket from DCA?

ASSISTANT: Sure, I am here to help you. May I know your travel dates please?

USER: I want to start my journey on May 14th and return on May 16th.

ASSISTANT: Ok, hold on for a moment. Let me check the best flight for you.

USER: Ok.

ASSISTANT: Sorry Dorothy, there are no flights available on your requested dates.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Thank you for choosing us. Have a great day.