MVC RouteConfig, Route determinated controllers - asp.net-mvc-4

Question

I want access to my principal pages (index, about, contact...) only with {action}{id}, but to the others with {controller}{action}{id}. For example:
A principal page: myweb.com/index
No principal page: myweb.com/Account/Login
I've searched but I don't know how do it exactly.
This is my RouteConfig
public class RouteConfig
{
public static void RegisterRoutes(RouteCollection routes)
{
routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
routes.MapRoute(
name: "Default",
url: "{controller}/{action}/{id}",
defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
);
/*routes.MapRoute(
"Account",
"Account/{AccountId}",
new { action = "Index", controller = "Course" }
);*/
/*routes.MapRoute(
name: "Default",
url: "{action}/{id}",
defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
);*/
/*routes.MapRoute(
"Account",
"Account/{courseId}",
//new { action = "Index", controller = "Course" }
new { controller = "Home", action = "Index" }
);*/
//routes.Add()
}
}

Answer 1

Change your routes config as below but you must have all your principal actions in one controller say PrincipalController as you will not be having controller in your routes.
Always map the high priority routes before low precedance routes.
public class RouteConfig
{
public static void RegisterRoutes(RouteCollection routes)
{
routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
routes.MapRoute(
name: "Principal",
url: "{action}/{id}",
defaults: new { controller = Princpal", action = "Index", id = UrlParameter.Optional }
routes.MapRoute(
name: "Default",
url: "{controller}/{action}/{id}",
defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
);
}
}

Answer 2

Please see example:
public class RouteConfig
{
public static void RegisterRoutes(RouteCollection routes)
{
routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
// Principal pages have unique route per each page.
// Methods About and Contact should be implemented in HomeController.
routes.MapRoute(
name: "About",
url: "about",
defaults: new { controller = "Home", action = "About" }
);
routes.MapRoute(
name: "Contact",
url: "contact",
defaults: new { controller = "Home", action = "Contact" }
);
// other pages use this default route
routes.MapRoute(
name: "Default",
url: "{controller}/{action}/{id}",
defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
);
}