You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Myself Jack Perez.

ASSISTANT: How can I help you Jack Perez?

USER: I want to visit White House.I want to book a ticket.

ASSISTANT: Sure, can you please help me with your airport codes?

USER: My airport codes are from DFW to IAD.

ASSISTANT: May I know your journey dates please?

USER: My trip dates are from 01/31 to 02/02.

ASSISTANT: Wait for a moment.

USER: Sure.

ASSISTANT: Sorry to say, there is no flight available on your preferred dates.

USER: Ok, that's fine.Thank you for your help.

ASSISTANT: Thank you and have a great day.