You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: I want to attend a business meeting with my client at Dallas, can you please book me a flight ticket under price of 200?

ASSISTANT: Sure, on which dates you wish to travel?

USER: My scheduled dates are from 10/19 to 10/21.

ASSISTANT: Please forward me your airport codes.

USER: My journey starts from Washington, DC-DCA to Dallas, TX-DFW.

ASSISTANT: Sorry for the inconvenience, there are no flights with your requirement at this moment.

USER: Ok, no problem.

ASSISTANT: May I know your name please?

USER: I am Edward Hernandez.

ASSISTANT: Thank you.

USER: Thank you.