You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you today?

USER: I am Brandon Phillips. I would like to travel from HOU to DEN. Can you please help me to book a ticket?

ASSISTANT: Sure, can you please share your travel dates?

USER: My travelling dates will be on Sept 1 to Sept 3.

ASSISTANT: Do you have any class preference?

USER: I am comfortable with any class.

ASSISTANT: Brandon Phillips, there is no flight available at your request.

USER: Ok, not an issue. Thank you.

ASSISTANT: Thank you for contacting us.