void electrons(char* newFile="DQM_new.root",char* refFile="DQM_old.root") {

  gROOT ->Reset();
  gROOT ->SetBatch();

  //=========  settings ====================
  gROOT->SetStyle("Plain");
  gStyle->SetPadGridX(kTRUE);
  gStyle->SetPadGridY(kTRUE);
  gStyle->SetPadRightMargin(0.07);
  gStyle->SetPadLeftMargin(0.13);
  //gStyle->SetTitleXSize(0.07); 
  //gStyle->SetTitleXOffset(0.6); 
  //tyle->SetTitleYSize(0.3);
  //gStyle->SetLabelSize(0.6) 
  //gStyle->SetTextSize(0.5);
  char* refLabel("reference histogram");
  char* newLabel("new histogram");

  delete gROOT->GetListOfFiles()->FindObject(refFile);
  delete gROOT->GetListOfFiles()->FindObject(newFile); 
  
  TText* te = new TText();
  TFile * sfile = new TFile(newFile);
  TDirectory * sdir=gDirectory;
  TFile * rfile = new TFile(refFile);
  TDirectory * rdir=gDirectory;

  if(sfile->GetDirectory("DQMData/EgammaV")) sfile->cd("DQMData/EgammaV/ElectronMcSignalValidator/");
  sdir=gDirectory;
  TList *sl= sdir->GetListOfKeys();
  //  sdir->ls();

  if(rfile->GetDirectory("DQMData/EgammaV")) rfile->cd("DQMData/EgammaV/ElectronMcSignalValidator/");
  rdir=gDirectory;
  TList *rl= rdir->GetListOfKeys();
  //  rdir->ls();

  TCanvas *canvas;

  TH1F *sh1,*rh1;
  TH1F *sh2,*rh2;
  
  rdir->GetObject("h_ele_ecalRecHitSumEt_dr04_barrel",rh1);
  sdir->GetObject("h_ele_ecalRecHitSumEt_dr04_barrel",sh1);

  rdir->GetObject("h_ele_ecalRecHitSumEt_dr04_endcaps",rh2);
  sdir->GetObject("h_ele_ecalRecHitSumEt_dr04_endcaps",sh2);

  canvas = new TCanvas("Electrons","Electrons",1000,1400);

  TH1F * r[2]={rh1,rh2};
  TH1F * s[2]={sh1,sh2};
  plotBuilding(canvas,s, r,2,
	       te,"UU",-1, 1, false, 0xC);

  canvas->cd();
  /*
  l = new TLegend(0.10,0.14,0.90,0.19);
  l->SetTextSize(0.016);
  l->SetLineColor(1);
  l->SetLineWidth(1);
  l->SetLineStyle(1);
  l->SetFillColor(0);
  l->SetBorderSize(3);
  l->AddEntry(rh1,refLabel,"LPF");
  l->AddEntry(sh1,newLabel,"LPF");
  l->Draw();
  */
  TString namepdf = "ecalIso04.pdf";
  canvas->Print(namepdf);   
  //  delete l;

  delete canvas;
}

void plotBuilding(TCanvas *canvas, TH1F **s, TH1F **r, int n,TText* te,
		  char * option, double startingY, double startingX = .1,bool fit = false, unsigned int logx=0){
  canvas->Divide(2,(n+1)/2); //this should work also for odd n
  for(int i=0; i<n;i++){
    s[i]->SetMarkerStyle(20);
    r[i]->SetMarkerStyle(21);
    s[i]->SetMarkerColor(2);
    r[i]->SetMarkerColor(4);
    s[i]->SetMarkerSize(0.7);
    r[i]->SetMarkerSize(0.7);
    s[i]->SetLineColor(1);
    r[i]->SetLineColor(1);
    s[i]->SetLineWidth(1);
    r[i]->SetLineWidth(1);
    // normalize
    r[i]->Scale(1./r[i]->Integral());
    s[i]->Scale(1./s[i]->Integral());

    TPad *pad=canvas->cd(i+1);
    setStats(s[i],r[i], -1, 0, false);
    if((logx>>i)&1)pad->SetLogx();
    r[i]->Draw();
    s[i]->Draw("sames");
  }

}

void setStats(TH1* s,TH1* r, double startingY, double startingX = .1,bool fit){
  if (startingY<0){
    s->SetStats(0);
    r->SetStats(0);
  } else {
    //gStyle->SetOptStat(1001);
    s->SetStats(1);
    r->SetStats(1);

    if (fit){
      s->Fit("gaus");
      TF1* f1 = (TF1*) s->GetListOfFunctions()->FindObject("gaus");
      f1->SetLineColor(2);
      f1->SetLineWidth(1);
    }
    s->Draw();
    gPad->Update(); 
    TPaveStats* st1 = (TPaveStats*) s->GetListOfFunctions()->FindObject("stats");
    if (fit) {st1->SetOptFit(0010);    st1->SetOptStat(1001);}
    st1->SetX1NDC(startingX);
    st1->SetX2NDC(startingX+0.30);
    st1->SetY1NDC(startingY+0.20);
    st1->SetY2NDC(startingY+0.35);
    st1->SetTextColor(2);
    if (fit) {
      r->Fit("gaus");
      TF1* f2 = (TF1*) r->GetListOfFunctions()->FindObject("gaus");
      f2->SetLineColor(4);
      f2->SetLineWidth(1);    
    }
    r->Draw();
    gPad->Update(); 
    TPaveStats* st2 = (TPaveStats*) r->GetListOfFunctions()->FindObject("stats");
    if (fit) {st2->SetOptFit(0010);    st2->SetOptStat(1001);}
    st2->SetX1NDC(startingX);
    st2->SetX2NDC(startingX+0.30);
    st2->SetY1NDC(startingY);
    st2->SetY2NDC(startingY+0.15);
    st2->SetTextColor(4);
  }
}