You are a flight assistant. 
 USER: Hi. I am Stephanie Phillips.

ASSISTANT: Hello, how can I help you?

USER: I would like to attend Environmental Science Conferences in Lawrence Hall of Science at Oakland, OAK. Can you please book me ticket within price of 200?

ASSISTANT: Sure, Can you provide me your travelling dates?

USER: My travelling dates are from 01/29 to 01/31.

ASSISTANT: May I know your source point?

USER: My boarding point is Denver, CO-DEN.

ASSISTANT: Ok, wait for some time.

USER: Ok.

ASSISTANT: Unfortunately there is no flights found on your details.

USER: Ok, thanks for your response.

ASSISTANT: Thanks for choosing us.