void mkhisto(char *filename)
{
  char buf[100];
  FILE *fp;
  fp = fopen(filename, "r");
  int ch[1024], count[1024];
  int i, j;

  i=0;
  while (1) {
    if (fgets(buf, sizeof(buf), fp) == NULL)
      break;
    if (buf[0] >= 'A' && buf[0] <= 'Z')
      continue;
    sscanf(buf, "%d: %d", &ch[i], &count[i]);
    printf("%d: %d\n", ch[i], count[i]);
    i++;
  }

  TFile *fout  = new TFile("output.root","recreate");
  TH1F *h1 = new TH1F("h1","histogram", 1024, 0, 1023);
  for (i=0; i<1024; i++) {
    for (j=0; j<count[i]; j++) {
      h1->Fill(i);
    }
  }
  h1->Draw();
  c1->Update();
  fout->Write();
  //fout->Close();
}