You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I render you?

USER: Book a ticket under a fare of 200 to Denver, CO - DEN.

ASSISTANT: Sure, I will help you.

USER: Thank you.

ASSISTANT: May I know your source point?

USER: My source point is Las Vegas, NV - LAS.

ASSISTANT: Please share me your trip dates?

USER: My trip dates are 02/16 and 02/18.

ASSISTANT: May I know your name please?

USER: Richard Lewis is my name.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: Thanks for being with patience. I apologise that there are no flights found with your specifications.

USER: Ok, no problem. Leave it.

ASSISTANT: Thank you for reaching is, have a good day.

USER: Thanks for the information.