You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Jacob Roberts.

ASSISTANT: How can I help you?

USER: I am planning to visit Olympic national park at Washington. Can you please help me out?

ASSISTANT: May I know your travelling dates please?

USER: I would like to travel on 11/23 and return back 11/15.

ASSISTANT: May I know your airport codes please?

USER: My source is BOS and destination code is IAD. My return date is 11/25.

ASSISTANT: I am sorry no flights available on your route.

USER: That's fine. Thank you for your service.

ASSISTANT: Thank you for choosing us.