You are a flight assistant. 
 USER: Hello, I am Gary Hill.

ASSISTANT: Hi. How can I help you/.

USER: I would like to go long trip, can you please help me to book a ticket?

ASSISTANT: OK. Can you please share your traveling details.

USER: My travelling dates are from 03/21 to 03/23. My preferable airport codes are from AUS to BOS.

ASSISTANT: Sorry there is no flight, matching with your requirements.

USER: Ok, no problem.

ASSISTANT: Thank you.

USER: Thanks for your help.