You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, How can I help you?

USER: My name is Samuel King, I want to book a flight ticket within a price limit of 500 for visiting a Heard Museum in Phoenix.

ASSISTANT: Sure, May I know the journey codes?

USER: My source and destination airport codes are DCA, PHX.

ASSISTANT: Please help me with your journey dates.

USER: My departure day is 04/02, return day is 04/04.

ASSISTANT: Please wait a minute.

USER: Sure.

ASSISTANT: Sorry, No flights found with your chosen dates.

USER: No problem, thank you for your service.

ASSISTANT: Thank you for availing us.