You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: Ruth Evans here. I want to travel from Houston to Washington for attending a Seminar. Can you please help me for booking the flight ticket?

ASSISTANT: Ok, can I have your travelling dates too?

USER: My travelling dates are from 10/26 to 10/28.

ASSISTANT: Sure, please mention your locations.

USER: My airport codes are from DCA to HOU.

ASSISTANT: Please wait a moment.

USER: Ok, I will wait.

ASSISTANT: Thanks for your time, there is no flight available on your route.

USER: Anyway, thanks for the information.

ASSISTANT: Thanks for choosing us.