use Data::Dumper;

my $arrref = [[1,1],2,[1,1]];

my $w = 0;
my $sum = 0;
my $text = Dumper($arrref);
while ($text =~ /(\[)|(\])|(\d+)/g) {
    $w++ if $1;
    $w-- if $2;
    $sum += $w * $3 if $3;
}

print $sum, "\n";  # "10"