void PlotEtas(const char* filename = "ETAS.root")
{
  TFile* file = new TFile(filename);
  TNtuple* etas = (TNtuple*)file->Get("etas");
  TH1F* m = new TH1F("m", ";m_{#gamma#gamma} [GeV/c^{2}];Counts/10 MeV", 100, 0, 1);
  m->SetFillColor(kCyan);
  etas->Project("m", "m");
  TString formula = "gaus(0)+gaus(3)+pol2(6)";
//   TString formula;
//   formula += "[0]*TMath::BreitWigner(x,[1],[2])+";
//   formula += "[3]*TMath::BreitWigner(x,[4],[5])+";
//   formula += "pol2(6)";
  TF1* fit = new TF1("fit", formula, 0.1, 1);
  fit->SetParameters(21, 0.13, 0.013, 12, 0.49, 0.022, 0.78, 22, -21);
  m->Fit(fit, "R");
  float xmin = 0.45; // fit->GetParameter(4) - 0.05;
  float xmax = 0.55; // fit->GetParameter(4) + 0.05;
  TLine* line1 = new TLine(xmin, 0, xmin, m->GetMaximum());
  TLine* line2 = new TLine(xmax, 0, xmax, m->GetMaximum());
  line1->SetLineColor(kRed);
  line2->SetLineColor(kRed);
  line1->Draw();
  line2->Draw();
  TF1* signal = new TF1("signal", "gaus", xmin, xmax);
  TF1* background = new TF1("background", "pol2", xmin, xmax);
  signal->SetParameters(fit->GetParameters() + 3);
  background->SetParameters(fit->GetParameters() + 6);
  float signalCounts = signal->Integral(xmin, xmax) / 0.010;
  float backgroundCounts = background->Integral(xmin, xmax) / 0.010;
  cout << "Signal = " << signalCounts << endl;
  cout << "Background = " << backgroundCounts << endl;
}