// *** the files coming from the simulation
  TString inSimFile  = "./data/epem_mom3.3_gegm0.0_seed1001sim.root"; // this file contains the MC truth
  TString inRecoFile = "./data/epem_mom3.3_gegm0.0_seed1001reco.root";
  TString inPidFile  = "./data/epem_mom3.3_gegm0.0_seed1001pid.root"; // this file contains the PndPidCandidates
  //TString inParFile  = "./data/epem_mom3.3_gegm0.0_seed1001params.root";

  TString inSimFile_bg  = "./data/pipi_mom3.3_costheta0.9_seed10000sim.root"; // this file contains the MC truth
  TString inRecoFile_bg = "./data/pipi_mom3.3_costheta0.9_seed10000reco.root";
  TString inPidFile_bg  = "./data/pipi_mom3.3_costheta0.9_seed10000pid.root"; // this file contains the PndPidCandidates
  //TString inParFile_bg  = "./data/pipi_mom3.3_costheta0.9_seed10000params.root";

  // *** initialization
  FairRunAna* fRun = new FairRunAna();
  FairRuntimeDb* rtdb = fRun->GetRuntimeDb();
  // *** add signal files
  fRun->SetInputFile(inSimFile);
  fRun->AddFriend(inPidFile);
  fRun->AddFriend(inRecoFile);
  // *** add background files
  fRun->SetBackgroundFile(inSimFile_bg);
  fRun->AddBackgroundFile(inPidFile_bg);
  fRun->AddBackgroundFile(inRecoFile_bg);

  TFile *file_sig = new TFile("./data/epem_mom3.3_gegm0.0_seed1001params.root","READ");
  TFile *file_bg = new TFile("./data/pipi_mom3.3_costheta0.9_seed10000params.root","READ");

  TList *list = new TList();
  list->Add(file_sig);
  list->Add(file_bg);

  FairParRootFileIo* parIO = new FairParRootFileIo();
  parIO->open(list);
  rtdb->setFirstInput(parIO);