You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Mary Young.

ASSISTANT: How can I assist you?

USER: I would like to book a ticket from DEN to IAD to meet my uncle, can you help me in booking?

ASSISTANT: Sure, can I know your travel dates?

USER: I am departing on 07/16 and return on 07/19.

ASSISTANT: Please give me a minute.

USER: Sure.

ASSISTANT: Mary, there is no flight available on your request.

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

ASSISTANT: You are welcome.