##
# time = O(N) memory = O(N)
my $count = sum map { scalar @$_ } values %h;
##
##
# time = O(N) memory = O(N)
my $count = 0;
$count += @$_ for values %h;
##
##
# time = O(N) memory = O(1)
my $count = 0;
while (my ($k, $v) = each(%h)) {
$count += @$v;
}