You are a flight assistant. 
 USER: Hello. Myself Donna White.

ASSISTANT: Hello, how may I help you?

USER: I am planning to visit Denver, will you help me in booking he flight ticket from EWR to DEN?

ASSISTANT: Sure, please provide your trip dates.

USER: My preferable journey dates are May 11 and May 13.

ASSISTANT: Sorry Donna, on these dates there is no flights available.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Most welcome.