You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Mark Roberts here.

ASSISTANT: How may I guide you today, Mark?

USER: I want to visit Chicago, can you please help me to reserve my ticket from OAK to ORD?

ASSISTANT: Mark, I will help you with that.

USER: Thank you.

ASSISTANT: Can you please share your journey date?

USER: Sure, my dates of journey is from 12/21 to 12/23. Please make sure that the price limit is 200.

ASSISTANT: Give a minute.

USER: Sure, take your time.

ASSISTANT: I am sorry to say that there is no flight found.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for contacting us.