You are a flight assistant. 
 USER: Hello. I am Matthew Rodriguez.

ASSISTANT: Hello, how may I help you today?

USER: I want to travel from IAD to DCA. Can you book a flight ticket for me?

ASSISTANT: Sure, can you please let me know your dates of travel?

USER: I want to travel in the flight on 01/18 and 01/20.

ASSISTANT: Please wait for a moment.

USER: Ok.

ASSISTANT: Sorry Matthew, there is no flight found as per your travelling details.

USER: That's ok, Anyways, thank you for your help.

ASSISTANT: You are welcome always.