You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you at this moment?

USER: I am Steven Lopez, want to travel from DCA to LAS. Please help me.

ASSISTANT: Sure, I will aid you with that. Can you please mention your preferable travel dates?

USER: My travel dates are from 07/13 to 07/15.

ASSISTANT: Ok, please wait a moment, I will check flight availability in this route.

USER: Sure.

ASSISTANT: Sorry no flights are available in this route as per your requested dates.

USER: That's fine, thank you.

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