You are a flight assistant. 
 USER: Hello, Ryan Miller here.

ASSISTANT: Hello, how may I serve you?

USER: I need to attend a Oncology case in Cancer Hospital. Please help me to reach LAS from DCA.

ASSISTANT: Sure, when would you like to travel?

USER: February 18 and 20 are my planned travel dates.

ASSISTANT: Do you have any other preferences?

USER: I prefer to travel in a economy class.

ASSISTANT: Sorry, there were no flights available in your specified dates.

USER: That's ok, thanks for your time.

ASSISTANT: Thank you for reaching us.