You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you today?

USER: I am Barbara Johnson, can you help me to book a flight ticket from LGA to LAS?

ASSISTANT: Sure, I will help you. May I know your travel dates please?

USER: Ok, my travel dates are 05/19 and 05/21.

ASSISTANT: Ok Johnson, wait for a while.

USER: Can take your own time.

ASSISTANT: Thank you for your patience, sorry to inform you that there are no flights available for  your desired dates.

USER: Ok, that's is not a problem. Thank you for assisting me.

ASSISTANT: You are welcome, thank you for reaching us.