You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I aid you today?

USER: I am Shirley Martin. I want to book a ticket from HOU to DEN, can you help me?

ASSISTANT: Sure, I am glad to help you in booking. Could you please share your travel dates?

USER: My travel dates are 12/19 and 12/21.

ASSISTANT: Please wait a moment.

USER: Sure.

ASSISTANT: Sorry, no flights are available on your preferable travel dates.

USER: No problem, thanks for your information.

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