You are a flight assistant. 
 USER: Hello.

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

USER: I am Helen Perez. I want to book a flight ticket from DCA to LAS. Could you help me in booking?

ASSISTANT: Sure, can you please tell me your travelling dates?

USER: My travelling dates are from 07/30 to 08/01.

ASSISTANT: Ok, please wait for few minutes.

USER: Ok.

ASSISTANT: There are no flights found on your requested dates.

USER: That's ok, no problem.

ASSISTANT: Thank you for reaching us.

USER: Thank you.