void tefficiency2D(){
  const int nbinsx = 5;
  const int nbinsy = 5;
  TH2D *hpassed = new TH2D("hpassed","Passed histograms",nbinsx,0,5,nbinsy,0,5);
  TH2D *hall = new TH2D("hall","All histograms",nbinsx,0,5,nbinsy,0,5);
  //filling histograms
  for (int ibinx = 1; ibinx <= nbinsx;ibinx++){
    for (int ibiny = 1; ibiny <= nbinsy; ibiny++){
      if (ibiny < 3) hpassed->SetBinContent(ibinx,ibiny,5);
      if(ibiny < 4) hall->SetBinContent(ibinx,ibiny,10);
   }
  }
  //plotting efficiency
  TEfficiency *heff = new TEfficiency(*hpassed,*hall);
  TH2* th2 = heff->CreateHistogram();
  TCanvas *c = new TCanvas();
  for (int ibinx = 1; ibinx <= nbinsx;ibinx++){
    for (int ibiny = 1; ibiny <= nbinsy; ibiny++){
     if (heff->GetTotalHistogram()->GetBinContent(ibinx,ibiny) == 0) th2->SetBinContent(ibinx,ibiny,-2);
    } 
  }
  th2->SetMinimum(-0.01);
  th2->Draw("COLZ");
}