#!/usr/bin/perl -w
$string="CMCDXCXLIXIVI"; @letters=split //,$string;
foreach $i (1 .. 2 ** scalar @letters) {
  %used=();$number="";$k=$i;
  foreach ($j=0; $j<=$#letters;$j++,$k >>= 1) {
    $letter=$letters[$j]; 
    if ($k % 2 and !$used{$letter}) {
      $used{$letter}=1; $number.=$letter;
    }
  }
  if (!$seen{$number}){
    $seen{$number}=1;
    print "$number\n";
  }
}