You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you?

USER: Please book a flight ticket from DEN to IAD.

ASSISTANT: May I know your name please?

USER: Samuel Parker here.

ASSISTANT: Can you please provide me your planning dates?

USER: Apr, 18 and Apr, 20 are my planned travel dates.

ASSISTANT: May I know Is there any preferences with airlines and class?

USER: No, thank you.

ASSISTANT: Ok, is there any connection requirements?

USER: Yes, I need to travel in direct flight.

ASSISTANT: Sorry, there are no flights available on you way.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for contacting us.