#!/usr/bin/perl -l
$_ = shift;

print"$_ is",(grep$_>1,map++$c{$_},split//)?"n't":'',' an isogram';

##</code><code>##

$ perl isogram.pl greet
greet isn't an isogram

$ perl isogram.pl isogram
isogram is an isogram

$ perl isogram.pl discrete
discrete isn't an isogram

##</code><code>##

sub is_iso {
(grep$_>1,map++$c{$_},split//,shift)?1:0
}


$_ = shift;
print "$_ is", ( is_iso($_)? "n't" : '' ), ' an isogram';


##</code><code>##

s**lil*;  $*=join'',sort split q**;  s;.*;grr; &&s+(.(.)).+$2$1+; $; =
qq-$_-;s,.*,ahc,;$,.=chop for split q,,,reverse;print for($,,$;,$*,$/)