You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Susan Gonzalez here.

ASSISTANT: How can I help you?

USER: Can you reserve a flight ticket with price below 500. My airport codes for boarding the flight are DCA to DEN.

ASSISTANT: Sure, I will help you to reserve your ticket. Can you please share me your travelling dates?

USER: My travelling dates for journey are 12/20 to 12/22. I need a direct flight.

ASSISTANT: Please hold on for a moment.

USER: Sure.

ASSISTANT: Sorry Susan, no flight is found on your route with 0 connection.

USER: Ok, not a problem. Thank you.

ASSISTANT: Welcome, have a nice day.