     ...........
    $2/,,,,$1...../
   $2/,,,$1..$2,,$1../   $2()
  $2/,,,,$1../
 $2/,,,$1.../     $1/'\
$2/,$1...../      $2\,/
$2\,,,,,,\\             $1_
 $2\,,$1....\\           $1/ \
  $1\...$2,$1..\\          $2\_/
   $1\..$2,,,,,,,,,,,,/
    $1\$2,,$1........$2,,/