use strict;
my $dir = '.';
print &dir_tree_size($dir) . "\n";
exit 0;

sub dir_tree_size {
  my $dir = shift;
  my ($i,$total);
  $total = 0;
  opendir DIR, $dir;
  my @files = grep !/^\.\.?$/, readdir DIR;
  for $i (@files) {
    if(-d $i) { $total += dir_tree_size($dir . "/$i") }
    else { $total += -s $i}
  }
  return $total;
}