http://stackoverflow.com/questions/15043981/how-to-access-json-decoded-array-in-php

http://www.proto-star.com/2010/10/04/phpでjsonのobjectを扱う/
違うなぁ
http://stackoverflow.com/questions/10758897/parsing-json-array-with-php-foreach
http://php.net/manual/ja/function.count.php
http://php.net/manual/ja/ref.array.php