TFile *tree500_cernbuild(Int_t getFile = 0, Int_t print = 1)
{
   Int_t  Category;
   UInt_t Flag;
   Int_t  Age;
   Int_t  Service;
   Int_t  Children;
   Int_t  Grade;
   Int_t  Step;
   Int_t  Hrweek;
   Int_t  Cost;
   Char_t Division[4];
   Char_t Nation[3];

   // The input file cern.dat is a copy of the CERN staff data base from 1988
   TString filename = "cernstaff.root";
   TString dir = gROOT->GetTutorialDir();
   dir.Append("/io/tree/");
   dir.ReplaceAll("/./","/");
   FILE *fp = fopen(Form("%scernstaff.dat", dir.Data()), "r");

   TFile *hfile = 0;
   if (getFile) {
      // if the argument getFile =1 return the file "cernstaff.root"
      // if the file does not exist, it is created
      if (!gSystem->AccessPathName(dir + "cernstaff.root", kFileExists)) {
         hfile = TFile::Open(dir + "cernstaff.root"); //in $ROOTSYS/tutorials/io/tree
         if (hfile)
            return hfile;
      }
      // otherwise try $PWD/cernstaff.root
      if (!gSystem->AccessPathName("cernstaff.root", kFileExists)) {
         hfile = TFile::Open("cernstaff.root"); //in current dir
         if (hfile)
            return hfile;
      }
   }
   //no cernstaff.root file found. Must generate it !
   //generate cernstaff.root in $ROOTSYS/tutorials/io/tree if we have write access
   if (gSystem->AccessPathName(".", kWritePermission)) {
      printf("you must run the script in a directory with write access\n");
      return 0;
   }
   hfile = TFile::Open(filename, "RECREATE");
   auto tree = new TTree("T", "CERN 1988 staff data");
   tree->Branch("Category", &Category, "Category/I");
   tree->Branch("Flag", &Flag, "Flag/i");
   tree->Branch("Age", &Age, "Age/I");
   tree->Branch("Service", &Service, "Service/I");
   tree->Branch("Children", &Children, "Children/I");
   tree->Branch("Grade", &Grade, "Grade/I");
   tree->Branch("Step", &Step, "Step/I");
   tree->Branch("Hrweek", &Hrweek, "Hrweek/I");
   tree->Branch("Cost", &Cost, "Cost/I");
   tree->Branch("Division", Division, "Division/C");
   tree->Branch("Nation", Nation, "Nation/C");
   char line[80];
   while (fgets(line, 80, fp)) {
      sscanf(&line[0],"%d %d %d %d %d %d %d  %d %d %s %s",
      &Category, &Flag, &Age, &Service, &Children, &Grade, &Step, &Hrweek, &Cost, Division, Nation);
      tree->Fill();
   }
   if (print)
      tree->Print();
   tree->Write();

   fclose(fp);
   delete hfile;
   if (getFile) {
      //we come here when the script is executed outside $ROOTSYS/tutorials/io/tree
      hfile = TFile::Open(filename);
      return hfile;
   }
   return 0;
}