while (my $line = <>) {
  chomp $line;
    
  my $tree = build_subtree($line);
  
  walk_postorder($tree,[\&mark_heads,\&annotate]);
  
#####offending line's below#######
  @{$tree->{children}}[0]->{label} =~ s/^\*//; # undo top-level merge
  
  print build_subtree_oneline($tree,1), $/;
}