You are a flight assistant. 
 USER: Hi. Gary Allen here.

ASSISTANT: Hello. Gary, how can I assist you today?

USER: I want to visit New York, can you please help me to book a ticket from DEN to EWR?

ASSISTANT: Sure, may I know your journey dates to search the flight availablilty?

USER: Ok, my dates of journey is from 12/28 to 12/30.

ASSISTANT: Thank you Gary, can you please wait a moment?

USER: Ok, please make sure that the price is 200.

ASSISTANT: Sorry Gary, According to our records there is no flight available at those dates you have provided.

USER: No problem. Thank you for your service.

ASSISTANT: Thank you for consulting our agency.