my $B = $doc->selectNodes("A/B")->[$cpt]->nodeValue();
        my $D = $doc->selectNodes("A/C/D")->[$cpt]->nodeValue();

##</code><code>##

if(defined($A_list)){
    for my $cpt (0..$#$A_list) {
        ...
    }
    print "\n\n";
}