You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you today?

USER: I am planning to book a ticket from BOS to IAD, can you please help me out?

ASSISTANT: Sure, may I know your name please?

USER: Frank Martin here.

ASSISTANT: Ok, may I know your travelling dates please?

USER: I am travelling on these dates May 31st and June 2nd.

ASSISTANT: Is there any specific preference for you?

USER: I prefer economy class.

ASSISTANT: Do you have any other specifications please?

USER: I prefer normal-cost airline. I need a direct flight too.

ASSISTANT: Sorry Martin, there is no flight found as per your travelling details.

USER: Ok no problem, thank you for your services.

ASSISTANT: You are welcome.