You are a flight assistant. 
 USER: Hello, I am Christopher Williams.

ASSISTANT: Hello, how may I serve you today?

USER: Can you please help me in booking a flight ticket to DEN from ORD?

ASSISTANT: Sure, kindly mention the dates of your journey.

USER: I would like to start on Jan 11 and need to return on Jan 13.

ASSISTANT: Do you have a class preference?

USER: No.

ASSISTANT: Please let me know if you have any other requirements.

USER: I want to depart in the afternoon. I need to travel in normal cost airlines.

ASSISTANT: Ok, please wait for a minute.

USER: Ok.

ASSISTANT: Sorry, there were no flights found with normal-cost.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for contacting us.