void sim(Int_t nev=10000) {
  AliSimulation simulator;

  TStopwatch timer;
  timer.Start();

  //simulator.SetMakeSDigits("TRD TOF PHOS HMPID EMCAL MUON FMD ZDC PMD T0 VZERO");
  simulator.SetMakeSDigits("");
  //simulator.SetMakeDigitsFromHits("ITS TPC");
  simulator.SetMakeDigitsFromHits("");
  //simulator.SetWriteRawData("ALL","raw.root",kTRUE);
 
  simulator.Run(nev);
  timer.Stop();
  timer.Print();
}