You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Eric Evans.

ASSISTANT: How may I aid you Eric?

USER: I want to visit my brother for his birthday in SFO, could you help me in booking the ticket?

ASSISTANT: Sure, please let me know on which dates you want to travel?

USER: It's from 11/16 to 11/18.

ASSISTANT: Please provide the origin airport code?

USER: I am from Denver DEN.

ASSISTANT: Ok, there is a flight available with UA airlines for you. Shall I book the ticket?

USER: Please book the ticket.

ASSISTANT: Ok, your ticket has been booked and the flight number is 1001.

USER: Thank you for helping me out.

ASSISTANT: Thank you, have a great trip.