You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: Shirley Allen here. Can you help me in ticket booking from LGA to LAS?

ASSISTANT: May I know your desired travel dates please?

USER: My travelling dates are from 04/21 to 04/23.

ASSISTANT: There is no flight on your desired travel dates.

USER: That's fine, thank you.

ASSISTANT: Thank you for opting us.