You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am Anna Green. I am planning to attend music concert at HOU, can you please help me with booking a flight ticket from IAD?

ASSISTANT: Sure, may I know your travelling dates please?

USER: Sure, I would like to take off on 06/22 and return on 06/24.

ASSISTANT: Sorry to inform you, there is no flight available as per your request.

USER: Ok, no issues. Thank you for checking.

ASSISTANT: Most welcome.