You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: Can you help me to book a flight ticket from DEN to LAX?

ASSISTANT: Sure, I will help you. May I know your name?

USER: Ok, please book a ticket for the dates Mar 25th and Mar 27th respectively. My name is Brain Evans.

ASSISTANT: Thank you. Do you have any other specifications?

USER: Yes, I need a connecting flight.

ASSISTANT: Ok, please wait for a while.

USER: Ok, I will wait.

ASSISTANT: Sorry, there is no flight available on your given travel dates.

USER: That's ok, thank you for assisting me.

ASSISTANT: You are welcome and thank you for choosing us.