You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you?

USER: I am Michael Davis, want to travel from DEN to OAK. Please help me in booking my ticket.

ASSISTANT: Sure, may I know your trip dates?

USER: Sure, my travelling dates are from 07/05 to 07/07.

ASSISTANT: Sorry, there is no flight available.

USER: It's ok, thank you for your help.

ASSISTANT: Most welcome.