void plot_circle(){
  double x[5]={-4.612,-4.281,-3.906,-3.922,-3.906};
  double y[5]={12.16,12.14,11.81,11.27,11.3};
  double x0[1]={-4.61};
  double y0[1]={11.54};
  

  TH2F *hr13 = new TH2F("hr13","Track segments",
                        20,-10,0.,20,5,15);
  hr13->Draw();

  TGraph *g0=new TGraph(5,x,y); 
  g0->SetMarkerStyle(kFullCircle);
  g0->SetMarkerColor(1);
  g0->SetLineColor(1);

  g0->Draw("p");

  TGraph *g1=new TGraph(1,x0,y0); 
  g1->SetMarkerStyle(kFullCircle);
  g1->SetMarkerColor(2);
  g1->SetLineColor(2);
  g1->Draw("p");





}