my $segment = $_;
    my $start ="";
    my $end ="";
    my $middle ="";
    
    while ($segment =~ /^(<[a|b|c] id=\".*?\"\/>)/ || $segment =~ /^(\s+)/){
        $start .= $1;
        $segment =~ s/^\Q$1\E//;
    }

    while ($segment =~ /(\s+)$/ || $segment =~ /(<[a|b|c] id=\".*?\"\/>)$/){
        $end = "$1$end";
        $segment =~ s/\Q$1\E$//;
    }
        
    while ($segment =~ /^(<d id=\".*?\">).*?(<\/d>)/){
	----
    }

    print "start: \"$start\", middle: \"$middle\", end: \"$end\"\n";