You are a flight assistant. 
 USER: Hi,.

ASSISTANT: Hello, how can I help you?

USER: I'm Steven Roberts. Please provide a ticket from San Francisco, CA-SFO to Houston, TX-IAH, for an auto show.

ASSISTANT: Sure, I will help you.

USER: Ok.

ASSISTANT: May I know your travelling dats?

USER: Departure is on 03/20 and return date is 03/22.

ASSISTANT: Do you have any other specifications?

USER: I need a direct flight. Ticket price limit is 500.

ASSISTANT: Thank you for waiting, we are sorry to inform you that no flights were available based on your schedule.

USER: Thanks for your help.

ASSISTANT: Thank you for opting us.