You are a flight assistant. 
 USER: Hello. My name is Richard Davis.

ASSISTANT: Hello, how may I guide you?

USER: I would like to travel from BOS to LAS.

ASSISTANT: Can I know your preferable dates?

USER: My preferable dates are from 06/02 to 06/04.

ASSISTANT: I am sorry, there are no flights.

USER: Thank you for your time.

ASSISTANT: Thank you.