//STL 'n' stuff
#include <iostream>
//Root includes
#include <TROOT.h>
#include <TChain.h>

using namespace std;
int chaintest(){

  //const int kMaxm_genParticles = 4214;
  const int kMaxm_genParticles = 10000; //<===================
  Int_t           m_genParticles_;
  Float_t         m_genParticles_m_px[kMaxm_genParticles];   //[m_genParticles_]
  Float_t         m_genParticles_m_py[kMaxm_genParticles];   //[m_genParticles_]
  Float_t         m_genParticles_m_pz[kMaxm_genParticles];   //[m_genParticles_]

  TBranch        *b_McEventCollection_p4_GEN_EVENT_m_genParticles_;   //!
  TBranch        *b_m_genParticles_m_px;   //!
  TBranch        *b_m_genParticles_m_py;   //!
  TBranch        *b_m_genParticles_m_pz;   //!

  TChain* chain = new TChain("CollectionTree"); 
  chain->SetMakeClass(1);

  chain->Add("/afs/cern.ch/user/m/mackepr/public/EVNT.024150._00001.pool.root.1");
  chain->Add("/afs/cern.ch/user/m/mackepr/public/EVNT.024150._00002.pool.root.1");

  chain->SetBranchAddress("m_genParticles", &m_genParticles_, &b_McEventCollection_p4_GEN_EVENT_m_genParticles_);
  chain->SetBranchAddress("m_genParticles.m_px", m_genParticles_m_px, &b_m_genParticles_m_px);
  chain->SetBranchAddress("m_genParticles.m_py", m_genParticles_m_py, &b_m_genParticles_m_py);
  chain->SetBranchAddress("m_genParticles.m_pz", m_genParticles_m_pz, &b_m_genParticles_m_pz);

  Long64_t nentries = chain->GetEntriesFast();
  
  for (Long64_t chain_entry=0; chain_entry<nentries;chain_entry++) {
     Long64_t tree_entry = chain->LoadTree(chain_entry);
     if (tree_entry < 0) break;
     b_McEventCollection_p4_GEN_EVENT_m_genParticles_->GetEntry(tree_entry);
     cout<<m_genParticles_<<endl;
     b_m_genParticles_m_px->GetEntry(tree_entry);
     b_m_genParticles_m_py->GetEntry(tree_entry);
     b_m_genParticles_m_pz->GetEntry(tree_entry);
    }
  return 0;
}