{

 TFile f("working_dir_KpKm_invMass_63GeV/finalResult.root"); 
 f.ls();

 TCanvas *c1 = new TCanvas("c1","c1",400,250,899,699);
 c1->Range(-12, -12, 12, 12);
 c1->SetBorderSize(2);
 c1->SetFrameFillColor(0);

 TChain* chain = (TChain*) f.Get("invMass");

 Int_t numberOfFilters = TMath::Nint(chain->GetEntries());

 char str[1000];

 int FN = 0; // currently processed filter number 

 while(true)
 {

      if(FN==0) cout<<"\nNumber of filters =  "<<numberOfFilters<<"\n\n";

      Int_t filterNumber;
      TNtuple* ntpl = new TNtuple();

      chain->SetBranchAddress("FilterNumberBranch",  &filterNumber);
      chain->SetBranchAddress("InvMassNTupleBranch", &ntpl);

      TNtuple* ntplFN = new TNtuple(Form("invMass%06i", FN), Form("Filter #%i invarint mass", FN), "invMass");

      for(Int_t fn=0; fn<numberOfFilters; fn++)
      {
           chain->GetEntry(fn);

           if(filterNumber!=FN) continue;

           Float_t im;
           ntpl->SetBranchAddress("invMass", &im);
           
           Int_t numberOfEntries = TMath::Nint(ntpl->GetEntries());

           for(Int_t i=0; i<numberOfEntries; i++)
           {
                ntpl->GetEntry(i);
                ntplFN->Fill(im, 0.0); // the second variable is dummy
           }// end of for

           ntpl->ResetBranchAddresses();

      }// end of for

      if(TMath::Nint(ntplFN->GetEntries())==0) break;

      ntplFN->Draw(Form("invMass>>htemp%i", FN), "", "");
      TH1F* htemp = (TH1F*) gDirectory->Get(Form("htemp%i", FN));
      sprintf(str, "invMassHist%06i", FN);
      htemp->SetNameTitle(str, "K^{+}K^{-} invariant mass: Phobos PR04 (63 GeV)");
      htemp->SetFillColor(6); // purple
      c1->Update();
      sprintf(str, "KpKmInvMass_63GeV_filter%06i.gif", FN); c1->SaveAs(str);
      sprintf(str, "KpKmInvMass_63GeV_filter%06i.root", FN); c1->SaveAs(str);

      delete ntpl;
      delete ntplFN;
      chain->ResetBranchAddresses();
      FN++;

 }// end of while 

}