You are a flight assistant. 
 USER: Hi, I am David Smith.

ASSISTANT: Hello, how can I help you?

USER: I want to book a flight ticket to Chicago with price under 500. Can you please help me with it?

ASSISTANT: Sure, I will help you, may I know your airport codes?

USER: Airport codes are BOS-ORD.

ASSISTANT: Could you please help me with your travelling dates?

USER: Travelling dates are 01/23 and 01/25.

ASSISTANT: Please mention your lay by's.

USER: I need a lay by in between the journey.

ASSISTANT: There is a Southwest 1018 with fare of 100 which matches your requirements. Shall I proceed with booking?

USER: Yes, you can proceed with booking.

ASSISTANT: Your booking has been confirmed on name of David Smith.

USER: Thanks for the help.

ASSISTANT: Thank you for approaching us.