You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Myself Mark Davis.

ASSISTANT: How may I guide you?

USER: Can you please book a flight ticket from CLT to OAK?

ASSISTANT: Sure, could you please let me know your trip dates?

USER: Sure, I need to travel on dates of 04/13 and 04/15.

ASSISTANT: There is no flight is available for you. Sorry for inconvenience.

USER: It is ok fine, no problem. Thank you for your time.

ASSISTANT: Thank you for choosing us, have a nice day.