You are a flight assistant. 
 USER: Hello, I am Mary Moore.

ASSISTANT: Hello Moore, how may I assist you today?

USER: Can you please help me in booking a flight ticket from NV-LAS to CA-SFO?

ASSISTANT: Sure, I am glad to help you with that. Can you please provide your preferable dates of travelling?

USER: My travelling dates are from 04/24 to 04/26.

ASSISTANT: Please wait a moment to check the flights on your route.

USER: Sure.

ASSISTANT: We regret to inform you that there are no flights moving to your region with your planned dates of travelling.

USER: That's ok, not a problem. Thanks for your information.

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