You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I be at your service today?

USER: I am Steven Collins. I have planned to attend my cousin's wedding at Washington, DC - DCA. Can you please book a ticket from IAD?

ASSISTANT: Sure, can I have your journey dates?

USER: Planned dates are 07/30 and 08/01.

ASSISTANT: Do you have any other preferences?

USER: I need a flag stop in my journey. Price should not exceed 500.

ASSISTANT: Sorry, no airline is available to provide you service on your dates.

USER: That's Ok. Thanks for your help.

ASSISTANT: Thank you for choosing our service.