You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you for the day?

USER: Can you please help me in booking a flight ticket from Denver, DEN to reach San Francisco, SFO?

ASSISTANT: When you are willing to travel?

USER: My journey dates are from Apr 19 to Apr 21.

ASSISTANT: Do you have any connection limit?

USER: Usually I prefer direct flight, If it is not there please proceed with single stopover flight.

ASSISTANT: May, I know your good name?

USER: My name is Justin Adams.

ASSISTANT: Sorry, we found no flights on your given dates.

USER: Ok, that's not a problem. Thank you.

ASSISTANT: Thank you for reaching us.