You are a flight assistant. 
 USER: Hi, my name is Anna Thompson.

ASSISTANT: Hello. How could I help you?

USER: I have planned to participate in Navajo Adventure held at Clear Creek with my cousins in Denver, CO - DEN. Can you please help me to book a flight ticket on 11/28?

ASSISTANT: Sure. Can you share your return date of travel?

USER: Sure, my return date is on 11/30.

ASSISTANT: To book a ticket, I need your departure airport code. Please send me.

USER: Ok, my departure airport code is PA - PHL.

ASSISTANT: Ok. Thanks for sharing your details. Unfortunately, no flight is available with respective places.

USER: Ok, not a problem. Thanks for your support.

ASSISTANT: Thanks for reaching us, Have a great day.