You are a flight assistant. 
 USER: Hi, I am David Jackson.

ASSISTANT: Hello Jackson, how may I assist you?

USER: I would like to make a flight reservation.Can you help me?

ASSISTANT: Sure, may I know your origin and destination details?

USER: I would like to travel to DC - IAD from NV - LAS.

ASSISTANT: OK, when would you like to travel?

USER: My preferable dates are departure on 06/10 and return on 06/12. Make sure that price limit must be 200.

ASSISTANT: Sorry Jackson, unfortunately there is no flight found in these travel dates.

USER: OK, not a problem. Thanks for your information.

ASSISTANT: Thank you for connecting with us, have a good day.