#!/usr/bin/perl -w
use strict;
my $line;

print( $line = join( "", ('A' .. 'G'), reverse ( 'A'..'F' )), "\n" );
$line =~ tr/G/ /;
print( $line, "\n" );

while ($line !~ /^\s+$/) {
  $line =~ s/(\S)(\s+)\1/ $2 /;
  print( $line, "\n");
};