void tgraph()

{
  TFile *f = new TFile("proc11_bucket_9to12.root");
  //TFile *f = new TFile("bucket_9to12.root");
  //TFile *f = new TFile("mc13b_proc11.root");
  //TCanvas *c1 = new TCanvas("c1","abc",500,500);
 
  TTree *tree = (TTree*)f->Get("DstD0PiKSKS");
  
  TCanvas *c1 = new TCanvas("c1","Canvas_1",399,135,538,325);
  //TGraph *g = new TGraph();    
  
  tree->SetMarkerStyle(20);
  //c1->DrawFrame(1,1,2000,2000);
  tree->Draw("(Dst_M-Dz_M):Dz_M", "Dst_p_CMS>2.5 && KS1_flightDistance/(KS1_flightDistanceErr)>10&&KS2_flightDistance/(KS2_flightDistanceErr)>10");
  auto func = new TF1("func","1.96834-x",1.8,1.96834-0.13957061);
  func->Draw("same");
  
  TFile * f1 = new TFile("tgraph_data.root","RECREATE");
  c1->Write();
  
  
}