You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, what help can I do for you?

USER: I am Mathew Walker. Actually, I am planning to go my brother's marriage from AUS to OAK. Can you help me out?

ASSISTANT: That's good to hear. Sure, may I know your travelling dates?

USER: My preferable dates are 10/18 to 10/20.

ASSISTANT: Sorry for the inconvenience, there is no flight available for your dates.

USER: That's fine. Thank you for taking time to speak with me.

ASSISTANT: Thank you for your positive response.