You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Michelle Edwards.

ASSISTANT: How may I help you?

USER: I would like to visit Lady Bird Lake at Washington with my friend, please help me in booking a ticket from PHX to DCA.

ASSISTANT: Sure, please provide your trip dates.

USER: My travelling dates are 06/24 and return on 06/26.

ASSISTANT: Sorry, on these dates there is no flights available.

USER: No problem, thank you for your information.

ASSISTANT: Most welcome.