{
  unsigned int iMaxFolders = 500;
  unsigned int iMaxHists = 100;

  TH1* pDummyHist = new TH3D("h3_dummy","dummy",30,0,1,30,0,1,30,0,1);

  TFolder* pBase = new TFolder("root","root");
  TFolder* pSubfolder = 0;
  TH1* h = 0;
  for(int i = 0; i < iMaxFolders; ++i)
  {
    cout << i << endl;
    pSubfolder = new TFolder(TString::Format("subfolder_%d",i).Data(),TString::Format("subfolder_%d",i).Data());
    for(int j = 0; j < iMaxHists; ++j)
    {
      h = (TH1*)pDummyHist->Clone(TString::Format("subfolder_%d_hist_%d",i,j).Data());
      h->FillRandom("gaus",10000);
      pSubfolder->Add(h);
    }
    
    pBase->Add(pSubfolder);
  }

  TFile* out = TFile::Open("output.root","RECREATE");
  out->cd();
  pBase->Write();
  out->Close();
}