You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Anna Adams here.

ASSISTANT: How may I assist you?

USER: Could you book my ticket in a direct flight?

ASSISTANT: Sure, I am here to help you out. May I know your travelling dates please?

USER: My trip dates are Apr 19 and Apr 21.

ASSISTANT: Do you prefer any halt?

USER: I already mentioned.

ASSISTANT: May I know your airport codes please?

USER: I want to depart from SEA in the afternoon and reach LAS.

ASSISTANT: Anna Adams, there are no flights available in your route.

USER: No problem, thank you.

ASSISTANT: Thank you for choosing us.