#!/usr/bin/perl -w

use strict;

if( $#ARGV < 0 )
{
   die "$0 <key>\n";
}
my $key;
($key = shift) =~ s/[^a-zA-Z]//g;
my @offsets = map {$_ <= ord('Z') ? (ord('A') - $_ + 26) % 26
                                  : $_ - ord('a')}
                  unpack 'C*', $key || "a";

my %translate = ();
for(my $offset = 0; $offset < 26; $offset++)
{
   for(my $input = 0; $input < 256; $input++)
   {
      $translate{$input}{$offset} = $input;
   }
   for(my $input = 0; $input < 26; $input++)
   {
      foreach (ord('a'), ord('A'))
      {
         $translate{$_ + $input}{$offset} = $_ + ($input + $offset) % 26;
      }
   }
}

my $index = 0;
while( <> )
{
   foreach my $i (unpack 'C*')
   {
      my $c;
      ($c = chr($translate{$i}{$offsets[$index]})) =~ /[a-zA-Z]/ && $index++;
      $index %= $#offsets + 1;
      print $c;
   }
}