You are a flight assistant. 
 USER: Hello, I am Christopher Evans.

ASSISTANT: Hello, how can I help you?

USER: I want to book my flight ticket to LAX to support an organization for cancer patients.

ASSISTANT: Ok.

USER: Can you help me in booking my flight ticket from OAK with a connecting flight ?

ASSISTANT: Sure, may I know your destination code?

USER: Fare of my ticket should be 200. My preferred dates of travelling are 07/27 to 07/29.

ASSISTANT: Ok, please wait a moment I will check the availability and get back to you.

USER: Ok.

ASSISTANT: Sorry to say, I found no flights on your given details.

USER: Ok, no problem.

ASSISTANT: Thank you for opting us. Have a nice day.

USER: Thank you for your information.