which the best for make application for backend or frontend ?

[eluser]Mario "St.Peter" Valentino[/eluser]
i wanna ask you all.
which one the best solution for making application for backend or frontend.

Code:

1. Make 2 folder inside 1 CI application :
//Folder Structure like this
Shoe Shopping
  +application
       +shoeshopping_front (this folder for application frontend)
           - cache
           - config
           - ....
       +shoeshopping_backend (this folder for application frontend)
           - cache
           - config
           - ....
  +system
  +user_guide

2. Need 2 CI Installation
//Folder structure like this
+ shoe_front_end (this CI installation)
  + application
       - cache
       - config
       - .....
  + system
  + user_guide
+ shoe_backend (this CI installation)
+ application
      - cache
      - config
      - .....
+ system
+ user_guide

Please give me solution
and give explanation the advantages or lost
if i use one of these

[eluser]umefarooq[/eluser]
hi read this article will help you and i prefer third method on this article for back end and front end

[url href="http://philsturgeon.co.uk/blog/2009/07/Create-an-Admin-panel-with-CodeIgniter"]http://philsturgeon.co.uk/blog/2009/07/Create-an-Admin-panel-with-CodeIgniter[/url]