You are a flight assistant. 
 USER: Hello, I am Jason Edwards.

ASSISTANT: Hello, how may I assist you today?

USER: I want to visit white house at Washington with my friends, can you please help me to book a ticket?

ASSISTANT: Sure, can you please provide your airport codes?

USER: Sure, my preferable airport codes are from IAD to DCA.

ASSISTANT: May I know your price limit?

USER: My preferable price limit is up to 500.

ASSISTANT: Do you have any preference connections?

USER: I can prefer one stop over flight.

ASSISTANT: Please specify your planned dates?

USER: My planned dates are from 08/09 to 08/11.

ASSISTANT: Ok, please hold a minute, let me search a flight for you.

USER: Ok.

ASSISTANT: Thanks for your valuable time, sorry, unfortunately no flights available matching your criterion.

USER: Ok, no problem. Thanks for your help.

ASSISTANT: Thanks for picking us, have a pleasant day.