You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: My name is Gary Taylor. I want to book a ticket from DEN to IAD to attend seminar in Washington, can you please help me?

ASSISTANT: Gary, I am happy to help you. Can you please tell me your travel dates?

USER: I am departing on 01/26 and return on 01/28.

ASSISTANT: Ok, please wait for a while. I will get back to you.

USER: Sure.

ASSISTANT: Sorry Gary, there are no flights available to IAD on 01/26.

USER: That's ok, thank you for your information.

ASSISTANT: Thank you for choosing us and have a nice day.