You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I assist you?

USER: I am Mary Harris. I am planning to travel from IAD to LAS, can you help in booking a flight for me?

ASSISTANT: Sure, may I know your planned travel dates please?

USER: I like to travelling dates are 05/11 to 05/13.

ASSISTANT: Please wait for a moment.

USER: Sure.

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

USER: That's ok, thank you for your help.

ASSISTANT: You are most welcome.