void bin_histo()
{
  
 
  TFile *f = new TFile("DtoKpipi0_RS_mc14ri_a_withoutenergy.root");

  TTree *tree  = (TTree*)f->Get("DstD0PiKPiPi0RS_withcut");

  Double_t  pi0_m_prefit, pi0_errm;

  tree->SetBranchAddress("pi0_m_prefit",&pi0_m_prefit);
  tree->SetBranchAddress("pi0_errm",&pi0_errm);
 


  Double_t pi0_M_PDG = 0.1349768;


  TH1F *h1 = new TH1F("pi0_M_preFit_0to0.0031","",100, 0.1, 0.18);
  TH1F *h2 = new TH1F("pi0_M_preFit_0.0031to0.00349","",100, 0.1, 0.18);
  TH1F *h3 = new TH1F("pi0_M_preFit_0.00349to0.00375","",100, 0.1, 0.18);
  TH1F *h4 = new TH1F("pi0_M_preFit_0.00375to0.00395","",100, 0.1, 0.18);
  TH1F *h5= new TH1F("pi0_M_preFit_0.00395to0.00411","",100, 0.1, 0.18);

  TH1F *h6 = new TH1F("pi0_M_preFit_0.00411to0.00424","",100, 0.1, 0.18);
  TH1F *h7 = new TH1F("pi0_M_preFit_0.00424to0.00435","",100, 0.1, 0.18);
  TH1F *h8 = new TH1F("pi0_M_preFit_0.00435to0.00446","",100, 0.1, 0.18);
  TH1F *h9 = new TH1F("pi0_M_preFit_0.00446to0.00456","",100, 0.1, 0.18);
  TH1F *h10 = new TH1F("pi0_M_preFit_0.00456to0.00468","",100, 0.1, 0.18);
  
 

 

  Int_t nentries = (Int_t)tree->GetEntries();
  for (Int_t i=0; i<nentries; i++)
    {
      tree->GetEntry(i);
 
      
     if(pi0_errm > 0 && pi0_errm < 0.0031)

        {

          h1->Fill(pi0_m_prefit);
          h1->GetXaxis()->SetTitle("pi0_M_preFit [GeV/c^{2}]");
          h1->GetXaxis()->SetTitleSize(0.05);
          h1->GetXaxis()->CenterTitle();
          //h1->SetLineWidth(2);

        
        } 
 

      if(pi0_errm > 0.0031 && pi0_errm < 0.00349)

        {

          h2->Fill(pi0_m_prefit);
          h2->GetXaxis()->SetTitle("pi0_M_preFit [GeV/c^{2}]");
          h2->GetXaxis()->SetTitleSize(0.05);
          h2->GetXaxis()->CenterTitle();
          //h2->SetLineWidth(2);

         
        } 
 
      if(pi0_errm > 0.00349 && pi0_errm < 0.00375)

        {

          h3->Fill(pi0_m_prefit);
          h3->GetXaxis()->SetTitle("pi0_M_preFit [GeV/c^{2}]");
          h3->GetXaxis()->SetTitleSize(0.05);
          h3->GetXaxis()->CenterTitle();
          //h3->SetLineWidth(2);

         
        } 
 
       if(pi0_errm > 0.00375 && pi0_errm < 0.00395)
        {

          h4->Fill(pi0_m_prefit);
          h4->GetXaxis()->SetTitle("pi0_M_preFit [GeV/c^{2}]");
          h4->GetXaxis()->SetTitleSize(0.05);
          h4->GetXaxis()->CenterTitle();
          //h4->SetLineWidth(2);

         
        } 
 
        if(pi0_errm > 0.00395 && pi0_errm < 0.00411)

        {

          h5->Fill(pi0_m_prefit);
          h5->GetXaxis()->SetTitle("pi0_M_preFit [GeV/c^{2}]");
          h5->GetXaxis()->SetTitleSize(0.05);
          h5->GetXaxis()->CenterTitle();
          //h5->SetLineWidth(2);

         
        } 
 
        if(pi0_errm > 0.00411 && pi0_errm < 0.00424)

        {

          h6->Fill(pi0_m_prefit);
          h6->GetXaxis()->SetTitle("pi0_M_preFit [GeV/c^{2}]");
          h6->GetXaxis()->SetTitleSize(0.05);
          h6->GetXaxis()->CenterTitle();
          //h6->SetLineWidth(2);

         
        } 
 
        if(pi0_errm > 0.00424 && pi0_errm < 0.00435)

        {

          h7->Fill(pi0_m_prefit);
          h7->GetXaxis()->SetTitle("pi0_M_preFit [GeV/c^{2}]");
          h7->GetXaxis()->SetTitleSize(0.05);
          h7->GetXaxis()->CenterTitle();
          //h7->SetLineWidth(2);

         
        } 
 
       if(pi0_errm > 0.00435 && pi0_errm < 0.00446)

        {

          h8->Fill(pi0_m_prefit);
          h8->GetXaxis()->SetTitle("pi0_M_preFit [GeV/c^{2}]");
          h8->GetXaxis()->SetTitleSize(0.05);
          h8->GetXaxis()->CenterTitle();
          //h8->SetLineWidth(2);

        
        } 
 

       if(pi0_errm > 0.00446 && pi0_errm < 0.00456)

        {

          h9->Fill(pi0_m_prefit);
          h9->GetXaxis()->SetTitle("pi0_M_preFit [GeV/c^{2}]");
          h9->GetXaxis()->SetTitleSize(0.05);
          h9->GetXaxis()->CenterTitle();
          //h9->SetLineWidth(2);

        
        }
 
       if(pi0_errm > 0.00456 && pi0_errm < 0.00468)

        {

          h10->Fill(pi0_m_prefit);
          h10->GetXaxis()->SetTitle("pi0_M_preFit [GeV/c^{2}]");
          h10->GetXaxis()->SetTitleSize(0.05);
          h10->GetXaxis()->CenterTitle();
          //h10->SetLineWidth(2);

        } 

  

   
    }
  

  if (gROOT->IsBatch()) return;
  new TBrowser();



  // TFile * f1 = new TFile("deltaM_Vs_MD0_2D_histo","recreate");
  // h1->Write();
  // h2->Write();
  
  // f1->Close();  
  
  

}