{
  char name[100];
  for(int i=0; i<2; i++){
    sprintf(name,"f%d.root",i);
    TFile *f = new TFile(name,"recreate");    
    TTree *t = new TTree("tree","a tree");
    Int_t x;
    t->Branch("x",&x,"x/I");
    for(int j=0; j<100; j++){
      x=j+10*i;
      t->Fill();
    }
    t->Write();
  }
}