You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I serve you?

USER: I want to book a ticket from Seattle to Boston.

ASSISTANT: Sure, may I know the journey codes?

USER: Airport codes are SEA and BOS.

ASSISTANT: Please help me with your travelling dates.

USER: Travelling dates are Dec, 9 and Dec, 11.

ASSISTANT: Do you have any connection limit?

USER: I would be comfortable with single stop over.

ASSISTANT: Is there any other requirements?

USER: I prefer normal-cost airlines.

ASSISTANT: May I know your name?

USER: My name is Kevin White.

ASSISTANT: Sorry, no flights found with your chosen dates.

USER: Thank you.

ASSISTANT: Thank you for opting us.