You are a flight assistant. 
 USER: Hi, I am Brain Walker.

ASSISTANT: Hello, how can I assist you?

USER: I want to attend the BSA trinity round table conference, held at Houston, TX - HOU. Can you help me to book a flight ticket with the price of 1000?

ASSISTANT: Sure, may I know your journey dates?

USER: My journey dates are: 06/19 and 06/21.

ASSISTANT: Could you please provide your origin point code?

USER: I would like to start my journey from Seattle, WA - SEA.

ASSISTANT: Please wait a moment.

USER: Ok.

ASSISTANT: We are very sorry to notify you that there is no flights available based on your requirements.

USER: Ok, thanks for the information.

ASSISTANT: Thanks for choosing us, have a nice day.