You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you?

USER: I am Mark Garcia, I am planning to visit my grand mother home in Los Angeles. So, please help me to book a flight ticket.

ASSISTANT: Sure, I am very happy to help you. Could you please provide me your travel dates?

USER: Sure, my travel dates are 06/16 and 06/18.

ASSISTANT: Ok, may I know your origin and destination airport codes?

USER: HOU and LAX are my origin and destination airport codes.

ASSISTANT: Sorry Mark, there is no flight available on your preferred travel dates.

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

ASSISTANT: You are welcome and thank you for contacting us.