#include <TChain.h>
#include <TFile.h>
#include <TTree.h>
#include <vector>

void AliESD_parser(
    std::string outName =
        "particles.txt",           // name of the output text file
    std::string inpName = "AliESDs.root", // name of the input ALIESD file
    std::string treeName = "esdTree",    // name of the tracks tree
    std::string pVertexBranchName = "PrimaryVertex.AliVertex.fPosition[3]", // name of the AliVertex position branch
    std::string tracksBranchName = "Tracks.fP[5]" // name of the tracks branch
) {

  ///-------> input
  TChain trackTree(treeName.c_str());
  trackTree.AddFile(inpName.c_str());

  TBranchElement *pVertexBranch = (TBranchElement*)trackTree.GetBranch(pVertexBranchName.c_str());

  std::cout << "trackTree.GetEntries(): " << trackTree.GetEntries() << std::endl;

  std::cout << "pVertexBranch->GetEntries(): " << pVertexBranch->GetEntries() << std::endl;

for (int n = 0; n < pVertexBranch->GetEntries(); n++) {
  pVertexBranch->GetEntry(n);
  double vertex[3];
  for(int i =0 ; i < 3 ; i++) {
    vertex[i] =   pVertexBranch->GetValue(i, sizeof(double));
  }
  std::cout << "Vertex for Entry " << n << " " << vertex[0] << " " << vertex[1] << " " << vertex[2] << std::endl;
}




}