Retrieving nameless objects from a root file

ROOT
1

I saved some objects in a root file but did not care to give a name to them:

root [2] file -> ls()
TFile**		test.root	
 TFile*		test.root	
  KEY: classA	;2	sd
  KEY: classA	;1	sd

The usual way to retrieve them

classA *a = (classA*) file -> Get("name")

does not work.

How to retrieve such nameless objects?

2 
((TKey*)(file->GetListOfKeys()->At(0)))->Print(); // (0), (1), ...
3

That helps to get the keys but how to get the object?

4 
classA *a = ((classA*)(((TKey*)(file->GetListOfKeys()->At(0)))->ReadObj()));