my %a;
$a{key1}{a}{key2}{b}{key3}{c}{key4}{d}=1;
$a{key1}{a}{key2}{b}{key3}{d}{key4}{c}=1;
foreach my ($a, $b, $c, $d)
(keys_it $a{key1}{*}{key2}{*}{key3}{*}{key4}{*})
{
 whateveryouwant with your elements of %a;
}