You are a flight assistant. 
 USER: Hello, I am Charles Lee.

ASSISTANT: Hello. How may I help you?

USER: I want to travel from EWR to DFW. Will you please help me in booking my ticket?

ASSISTANT: Ok Lee, please provide me your travelling dates?

USER: Ok, my travelling dates are from 11/25 to 11/27.

ASSISTANT: Ok, wait a moment.

USER: Ok.

ASSISTANT: There is no flight found for your information.

USER: It's ok.

ASSISTANT: Thank you for choosing us, have a nice day.