my $i = 1;

    while ( <A> ) {
        my $file = ( split /\n/, $_ )[1] or next;
        ( $file ) = $file =~ m/"(.*?)"/ or next;

        $file = $i;
        open B, "> $file.csv"
            or warn( "Cannot open '$file': $!" ), next;
        print "[DEBUG] '$file': open ok\n";
        chomp $_;
        print B $_;
        close B or warn( "Cannot close '$file': $!" ), next;
        print "[DEBUG] '$file': close ok\n";
        $i++;
    }