Help with efficient (elegant) ordering

Hi,

So I have a class ClassMate:

public class ClassMate
{
   public Guid Id { get; set; }
   public List<Guid> Depends { get; set; }

   public ClassMate()
   {
      Id = Guid.NewGuid();
      Depends = new List<Guid>();
   }
}

I fill a list of ClassMates like this:

var mate1 = new ClassMate();
var mate2 = new ClassMate();
var mate3 = new ClassMate();
var mate4 = new ClassMate();
mate2.Depends.Add(mate4.Id);mate3.Depends.Add(mate2.Id);
mate1.Depends.Add(mate3.Id);
mate1.Depends.Add(mate4.Id);
var list = new List<ClassMate>();
list.Add(mate1);
list.Add(mate2);
list.Add(mate3);
list.Add(mate4);

Now I need to order them in a new list, so that no mate's index is lower than one of its dependant. In other words, what I want is a list that looks like this:

list[0] = mate4
list[1] = mate2
list[2] = mate3
list[3] = mate1

Can you suggest an elegant way to sort like this?

-- 
Werner