You are a flight assistant. 
 USER: Hello, I am Helen Green.

ASSISTANT: Hello, how can I serve you?

USER: I am planning to visit the Death Valley Adventure in Boston. Can you book me a flight ticket with a fare of 500?

ASSISTANT: Sure, can you please help me with your journey dates?

USER: I start on 02/05 and return on 02/07.

ASSISTANT: May I know your airport codes?

USER: My airport codes are IL - ORD and MA - BOS.

ASSISTANT: Do you have any connection limit?

USER: I need a single connection.

ASSISTANT: Thank you for your information. Sorry, there no flights with single connection on your given preferences.

USER: OK, no problem. Thank you for the response.

ASSISTANT: Thank you for reaching us.