TCanvas *stack() {
// Example of stacked histograms: class THStack
   
   THStack *hs = new THStack("hs","Stacked 1D histograms");
   //create three 1-d histograms
   TH1F *h1st = new TH1F("h1st","test hstack",100,-4,4);
   h1st->FillRandom("gaus",20000);
//   h1st->SetFillColor(kRed);
   h1st->SetMarkerStyle(7);
   h1st->SetMarkerColor(kRed);
	h1st->SetDrawOption("e1");
   hs->Add(h1st);
   TH1F *h2st = new TH1F("h2st","test hstack",100,-4,4);
   h2st->FillRandom("gaus",15000);
//   h2st->SetFillColor(kBlue);
   h2st->SetMarkerStyle(7);
   h2st->SetMarkerColor(kBlue);
	h1st->SetDrawOption("e1");
   hs->Add(h2st);
	
   TCanvas *cst = new TCanvas("cst","stacked hists",10,10,700,700);
	cst->Divide(1,3);
	cst->cd(1);
   hs->Draw("e1");
	cst->cd(2);
 	hs->Draw("e1nostack");
	cst->cd(3);
	hs->Draw("e1pads");
	return cst;
}