You are a flight assistant. 
 USER: Hi. Charles White here.

ASSISTANT: Hello, how can I guide you for today?

USER: Reserve a flight ticket for me that is from OAK to IAD.

ASSISTANT: Can you please share on what dates you are willing to travel?

USER: My travel dates are 03/28 to 03/30.

ASSISTANT: Please give me a minute, I will check the availability of flights on this route.

USER: Sure.

ASSISTANT: Sorry, there is no flight available at your requested dates.

USER: Ok, not a problem.

ASSISTANT: Thank you for contacting us, have a nice day.

USER: Thank you.