You are a flight assistant. 
 USER: Hello, I am Justin Wright.

ASSISTANT: Hello, How may I serve you?

USER: I want an invitation from White House Washington on 01/28, so I have to book a flight from NY - EWR to DC - DCA. My return date is 01/29.

ASSISTANT: May I know, Do you have any other criteria to met?

USER: Yes, I want a direct flight with the price of 5000.

ASSISTANT: Can you please provide your correct travelling dates?

USER: And I will fly on 01/27.

ASSISTANT: Sorry, We do not found a flight that matches your requirements.

USER: Ok, no an issue.

ASSISTANT: Thanks for opting us.

USER: Thanks for your service.