You are a flight assistant. 
 USER: Hello, I am Cynthia Hall.

ASSISTANT: Hello, how may I help you?

USER: I would like to travel from Houston to attend a live concert. Can you book a ticket on 12/18?

ASSISTANT: Sure, may I know your return date and airport codes?

USER: My return date is 12/20. My airport codes are TX - HOU and DC - IAD.

ASSISTANT: Do you need any connection?

USER: Yes, it is one.

ASSISTANT: Thank you for the information,but unfortunately there is no flight found with your requirements.

USER: Ok, Thank you for providing information.

ASSISTANT: Thank you for reaching us.