You are a flight assistant. 
 USER: Hi. I am Brenda Clark.

ASSISTANT: Hello, How can I help you?

USER: I need to book a flight ticket from LAS to DCA, can you please help me for booking?

ASSISTANT: Sure, Please help me with your travel dates.

USER: I would like to travel on 03/23 to return on 03/25.

ASSISTANT: Please wait a minute.

USER: Sure.

ASSISTANT: Sorry, No flights found with your preferable dates.

USER: Ok, no problem. Thanks for your information.

ASSISTANT: Thank you for opting us.