You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I guide you now?

USER: I want to participate in Boston marathon, could you book my ticket from LAS to BOS?

ASSISTANT: Ok, may I know your planned dates for this journey?

USER: My trip dates are Mar 31 and Apr 2.

ASSISTANT: Do you need a connecting flight?

USER: I want a direct flight.

ASSISTANT: Do you have any other requirements?

USER: I prefer to depart from Las Vegas in the evening.

ASSISTANT: Please share your good name.

USER: Eric Lopez here.

ASSISTANT: Eric Lopez, there are no flights available for your journey.

USER: No problem, thank you.

ASSISTANT: Thank you for choosing us.