void tree501_cernstaff()
{
   TString dir = gROOT->GetTutorialDir();
   dir.Append("/io/tree/cernstaff.C");
   if (gSystem->AccessPathName("cernstaff.root")) {
      gROOT->SetMacroPath(dir);
      gROOT->ProcessLine(".x tree500_cernbuild.C");
   }
   auto f = TFile::Open("cernstaff.root");
   auto T = f->Get<TTree>("T");
   auto c1 = new TCanvas("c1", "CERN staff", 10, 10, 1000, 750);
   c1->Divide(2, 2);
   // make table of number of people per Nation & Division
   c1->cd(1);
   gPad->SetGrid();
   T->Draw("Nation:Division>>hN", "", "text");
   TH2F *hN = (TH2F*)gDirectory->Get("hN");
   hN->SetMarkerSize(1.6);
   hN->SetStats(0);

   //make profile of Average cost per Nation
   c1->cd(2);
   gPad->SetGrid();
   gPad->SetLeftMargin(0.12);
   T->Draw("Cost:Nation>>hNation", "", "prof,goff");
   TH1F *hNation = (TH1F*)gDirectory->Get("hNation");
   hNation->SetTitle("Average Cost per Nation");
   hNation->LabelsOption(">"); //sort by decreasing bin contents
   hNation->SetMaximum(13000);
   hNation->SetMinimum(7000);
   hNation->SetStats(0);
   hNation->SetMarkerStyle(21);
   hNation->Draw();

   //make stacked plot of Nations versus Grade
   c1->cd(3);
   gPad->SetGrid();
   auto hGrades = new THStack("hGrades", "Nations versus Grade");
   auto hFR = new TH1F("hFR", "FR", 12, 3, 15);
   hFR->SetFillColor(kCyan);
   hGrades->Add(hFR);
   T->Draw("Grade>>hFR", "Nation==\"FR\"");
   auto hCH = new TH1F("hCH", "CH", 12, 3, 15);
   hCH->SetFillColor(kRed);
   hGrades->Add(hCH);
   T->Draw("Grade>>hCH","Nation==\"CH\"");
   auto hIT = new TH1F("hIT", "IT", 12, 3, 15);
   hIT->SetFillColor(kGreen);
   hGrades->Add(hIT);
   T->Draw("Grade>>hIT","Nation==\"IT\"");
   auto hDE = new TH1F("hDE","DE", 12, 3, 15);
   hDE->SetFillColor(kYellow);
   hGrades->Add(hDE);
   T->Draw("Grade>>hDE","Nation==\"DE\"");
   auto hGB = new TH1F("hGB","GB", 12, 3, 15);
   hGB->SetFillColor(kBlue);
   hGrades->Add(hGB);
   T->Draw("Grade>>hGB","Nation==\"GB\"");
   hGrades->Draw();
   auto legend = new TLegend(0.7, 0.65, 0.86, 0.88);
   legend->AddEntry(hGB,"GB","f");
   legend->AddEntry(hDE,"DE","f");
   legend->AddEntry(hIT,"IT","f");
   legend->AddEntry(hCH,"CH","f");
   legend->AddEntry(hFR,"FR","f");
   legend->Draw();

   //make histogram of age distribution
   c1->cd(4); gPad->SetGrid();
   T->Draw("Age");
   T->Draw("Age>>hRetired", "Age>(65-2002+1988)", "same");
   TH1F *hRetired = (TH1F*)gDirectory->Get("hRetired");
   hRetired->SetFillColor(kRed);
   hRetired->SetFillStyle(3010);

   auto arrow = new TArrow(32, 169, 55, 74, 0.03, "|>");
   arrow->SetFillColor(1);
   arrow->SetFillStyle(1001);
   arrow->Draw();

   auto pt = new TPaveText(0.12, 0.8, 0.55, 0.88, "brNDC");
   pt->SetFillColor(kWhite);
   pt->AddText("People at CERN in 1988");
   pt->AddText("and retired in 2002");
   pt->Draw();

   c1->cd();
}