You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Kathleen Carter here.

ASSISTANT: How can I help you at this moment?

USER: I would like to visit DEN to meet my sister, can you help me to book a flight ticket from LAS?

ASSISTANT: Kathleen Carter, I am here to help you for this. When you are planning to leave?

USER: My preferable dates are 10 and 12 of Dec.

ASSISTANT: Do you prefer any airlines?

USER: I am comfortable with any airlines.

ASSISTANT: Kathleen Carter sorry to intimate, no flights are found with your criteria.

USER: That's ok, thank you for giving information.

ASSISTANT: Thank you very much for reaching our agency.