void sub() {
 
   TFile *f = new TFile("Cf_source.root");
  TTree *t1 = (TTree*)f->Get("t1");
  Double_t PH1,ZCO1,TOF1;
 
  t1->SetBranchAddress("PH1",&PH1);
  t1->SetBranchAddress("ZCO1",&ZCO1);
  t1->SetBranchAddress("TOF1",&TOF1);

  TFile *f1 = new TFile("Cf_background.root");
  TTree *t2 = (TTree*)f1->Get("t2");
  Double_t bPH1,bZCO1,bTOF1;
 
  t2->SetBranchAddress("bPH1",&bPH1);
  t2->SetBranchAddress("bZCO1",&bZCO1);
  t2->SetBranchAddress("bTOF1",&bTOF1);

  TH1F *h1   = new TH1F("h1","bTOF1",100,0,4000);
  TH1F *h2 = new TH1F("h2","TOF1",100,0,4000);
 



 Int_t nentries = (Int_t)t1->GetEntries();
  for (Int_t i=0; i<nentries; i++) {
    t1->GetEntry(i);
    h1->Fill(TOF1);
 
   }

 Int_t bnentries = (Int_t)t2->GetEntries();
  for (Int_t i=0; i<bnentries; i++) {
    t2->GetEntry(i);
   h2->Fill(bTOF1);
 
   }
  
//h1->Draw();
//h2->Draw();
//TCanvas *c1 = new TCanvas("c1"," ",800,900);
//TH1F *h_out = (TH1F*)h1->Clone("difference");
//h_out->Add(h2, -1.);
//h_out->Draw("box");
h1->Add(h2, -1.);
h1->Draw();


}