push @structure , [];
for (my $i=0;$i<= $#ex; $i++) {
 push @{ @structure->[$j]}, $ex[$i]; 
}

##</code><code>##

foreach my $lev1 (@structure) {
  my $cnt = scalar(@{$lev1};
  foreach my $lev2 (@{$lev1}) {
	my %hash = %{$lev2};
	foreach my $key ( keys %hash )
	{ 		
	   # if ($key eq $xx) etc.
	}
   }
}