You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello,. How can I serve you?

USER: I am Janet Carter. I want to fly to Washington DC - DCA on 12/22 on the occasion of festival from Phoenix AZ - PHX on 12/24.

ASSISTANT: Sure, please wait a moment I will check and get back to you. We are very sorry to notify you that there is no flight available according to your criterion.

USER: OK, thanks for your assistance.

ASSISTANT: Thank you.