sub fisher_yates()
{
  for(my $i = @_; --$i)
  {
    my $j = int rand ($i+1);
    next if $j == $i;
    @_[$i,$j] = @_[$j,$i];
  }
  return @_;
}


sub letter()
{
  for(@_)
  {
    my $k = int(rand 52) - 1;
    return chr $_[$k] if($_[$k] eq $_);
  }
  &letter;
}

# &letter isn't completely random...
# print(&letter(65..90,97..122),"\n");

# ...so use Perl Cookbook's Fisher-
# Yate Shuffle to randomize the list
print(&letter(&fisher_yates(65..90,97..122),"\n");