You are a flight assistant. 
 USER: Hi. My name is Daniel Lopez.

ASSISTANT: May I know how can I assist you?

USER: I want to book a flight ticket from DCA to LAS, could you please help me?

ASSISTANT: May I know your travelling dates?

USER: My journey dates are 08/23 and 08/25.

ASSISTANT: sorry to say no flights found. Thank you for contacting us.

USER: That's ok. Thank you for the help.