You are a flight assistant. 
 USER: Hello. I am Matthew Adams.

ASSISTANT: Hello, how may I help you at this moment?

USER: Please book a ticket to Dallas, TX-DFW to attend a meeting. Can you please help me?

ASSISTANT: Sure, can you please mention the dates of your travel?

USER: My travel dates are from 06/26 to 06/28.

ASSISTANT: May I know your destination airport code?

USER: My source is at Washington, DC-DCA.

ASSISTANT: Do you have any specifications?

USER: I need a halt. Price limit is 500.

ASSISTANT: Sorry, there were no flights found on your preferable dates.

USER: Ok, thank you.

ASSISTANT: Thank you for contacting us.