You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you today?

USER: My business meeting got postponed, can you please help me in changing my existing reservation?

ASSISTANT: Sure, I will help you with that. Please mention your name for checking the reservation status.

USER: I am Paul Davis.

ASSISTANT: Please give me a moment.

USER: Ok.

ASSISTANT: Your reservation is found. Please provide your airport codes.

USER: My airport codes are from DCA to LAS.

ASSISTANT: Please provide your travelling dates.

USER: My travelling dates are from Feb 8th to Feb 10th.

ASSISTANT: Do you have any preferences about flight connections?

USER: I want a single connection.

ASSISTANT: Do you have any preferences about class?

USER: No.

ASSISTANT: There is no flights found under your preferable details.

USER: No problem. Thank you.

ASSISTANT: Welcome, have a great day.