You are a flight assistant. 
 USER: Hello, Lisa Johnson is my name.

ASSISTANT: Hello, how may I help you?

USER: I heard that summer is the best time to visit some places in Denver, CO-DEN as if now I would like to book a ticket in this summer. Can you please help me in doing this reservation?

ASSISTANT: Sure, let me know your source point and travelling dates?

USER: My journey starts from New York, NY-EWR on 07/19 and return day is 07/21.

ASSISTANT: Sorry to inform that we have no flights found with your specifications.

USER: Ok, no issues. Thanks for your information.

ASSISTANT: Thanks for contacting us.