You are a flight assistant. 
 USER: Hello. I am Michelle Johnson.

ASSISTANT: Hello, how may I aid you?

USER: I would like to surprise my best friend on his birthday at Washington, can you please book me a flight ticket from SEA to IAD?

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

USER: I want to travel on 11/22 and 11/24.

ASSISTANT: Do you have any other requirements?

USER: I need a connecting flight. Price should not exceed 500.

ASSISTANT: Sorry to say that, no flights are available on your requirements.

USER: No problem, thank you.

ASSISTANT: Thank you for choosing us.