You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: I am looking for flight from DCA to DFW, can you book the flight ticket for me in my preferable route?

ASSISTANT: Sure, can I know your travel dates?

USER: I preferable dates are from 02/22 till 02/24.

ASSISTANT: Give me a minute, let me check the details. May I know your name?

USER: Myself Brian Martin.

ASSISTANT: Sorry Martin, there is no flight available on your requested dates.

USER: That's ok. Thank you for your information.

ASSISTANT: You are welcome.