use strict;
use warnings;

my $str = do {local $/; <DATA>};
$str =~ s/\s+//g;
my $len = length $str;

for (my $width = 5; $width; --$width) {
  for (0..($len - $width)) {
    print substr ($str, $_, $width) . "\n";
  }
}

__DATA__
ABCDEFGHIJK