if ($INPUT{'fourthing'} eq "four") {
$address = "four.txt";
}  elsif ($INPUT{'fourthing'} eq "five") {
$address = "five.txt";
}    elsif ($INPUT{'fourthing'} eq "six") {
$address = "six.txt";
}    else  {&formula; }

##</code><code>##

$;=sub{$/};@;=map{my($a,$b)=($_,$;);$;=sub{$a.$b->()}}
split//,".rekcah lreP rehtona tsuJ";$\=$ ;->();print$/