How can I locate isolated facets (or group of facets) in a mesh using CGAL? Let's suppose I have a mesh file (STL, OBJ, ...), and I know it contains a closed solid and a group of facets that does not constitute another solid and is not connected to the aforementioned solid present in the file: how do I detect that isolated group of facets? For example, I can read an .STL file using CGAL::IO::read_STL(), but then I'm not able to do what I'm asking. Could you help me?