Authenticate two diffrent folder using forms authetication

 Hi,
    I am trying to autheticate two diffrent folder and i have two login page respectively in that two folder.
    Folder structure....
    --Admin--->>Admin_welcome.aspx , Admin_login.aspx
    --User----->>User_welcome.aspx , User_Login.aspx
 
Now i want when user acess the admin_welcome.aspx page it will be redirected to admin_login,aspx page for authenticate
and when user access the  user_welcome.aspx page it will be redirected to user_login,aspx page for authenticate
 
Please tell me how can i achieve this.
 
THanks in Advance.

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