You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Matthew Williams from Las Vegas.

ASSISTANT: How may I assist you?

USER: I have a corporate training to provide at Washington. Can you help me in booking a ticket?

ASSISTANT: Sure, may I know your airport codes please?

USER: The airport codes are LAS and IAD respectively.

ASSISTANT: Please provide your journey dates.

USER: The planned journey dates are 12/26 and 12/28.

ASSISTANT: Please wait a moment.

USER: Ok, take your time.

ASSISTANT: Williams, no flights has been found on your requested dates.

USER: Its ok, thank you for the information.

ASSISTANT: Thank you for reaching us.