You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you?

USER: I am Melissa Martin. Can you please help me in booking my flight ticket from DEN to LAS?

ASSISTANT: May i know your travelling dates please?

USER: Ok, my travelling dates are 12/24 and 12/26.

ASSISTANT: I am sorry no flights found on your dates.

USER: Ok, thank you for checking.

ASSISTANT: Thank you.