You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: Frank Miller here. I want to meet my cousin on his birthday at Houston, could you book my ticket from Chicago?

ASSISTANT: Sure, may I know your trip dates?

USER: I will be leaving on June 11 and June 13.

ASSISTANT: Can you please share you airport codes?

USER: My genesis and terminus airport codes are ORD and HOU.

ASSISTANT: Ok, please wait a minute.

USER: Sure.

ASSISTANT: Sorry to inform you that but there is no flights available.

USER: No problem, thank you.

ASSISTANT: Most welcome.