You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, How can I help you?

USER: I want to book a ticket from IAD to EWR as my brother wants to join in New York University.

ASSISTANT: Sure< May I know the price limit and travelling dates?

USER: And my  price should be of 500. My journey starts on 06/26 and ends on 06/28.

ASSISTANT: Ok, Wait a minute.

USER: Sure.

ASSISTANT: Thanks for waiting. Unfortunately, There is no flight available with your data.

USER: Ok, thank you for your service.

ASSISTANT: Thank you.