void openrun(int run, int nums,TString path="outfiles/parts")
{
  TChain* chain= new TChain("cbmsim");

  

  for (int i=0;i<=nums;i++)
    {
      if (i==0)
	chain->AddFile(Form("%s/runC_%d.smoothed_reco.root",path.Data(),run));
      else
	chain->AddFile(Form("%s/runC_%d.smoothed_reco%d.root",path.Data(),run,i));
      cout<<"adding file "<<i<<endl;
    }
}