You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I serve you?

USER: I am Sharon Evans. I want to book a ticket from Denver to Houston, can you book a direct flight please?

ASSISTANT: Sure, may I know your travelling dates?

USER: Yes, my travelling dates are 11/19 and 11/21.

ASSISTANT: Kindly share your journey codes.

USER: Sure, my airport codes are CO-DEN and TX-IAH.

ASSISTANT: Give me a minute.

USER: Ok.

ASSISTANT: I am sorry to inform that there is no flight available matching with your requirements.

USER: That's ok. Thank you for the response.

ASSISTANT: Thanks for availing us.