You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello,.

USER: I am Andrew Lee.

ASSISTANT: How may I assist you?

USER: I need to book a flight ticket from Los Angeles, CA-LAX to Denver, CO-DEN to meet my parents. Could you please help me with booking a flight ticket?

ASSISTANT: Sure. Please mention your travelling dates?

USER: Sure, 02/10 and 02/12 are my travelling dates.

ASSISTANT: No flight found to Denver. Thanks.

USER: No problem, thank you for your help.

ASSISTANT: Have a nice day!.