title: Messenger PHP chatbot receives more JSONs
body: <p>my PHP chatbot receives multiple JSONs with php://input. It gets input message (that's correct), but then it receives JSON with message sent by bot (response), delivery confirmation and read confirmation.</p>
  
  <p>How can I keep only that first JSON?</p>
  
  <p>I need it because it then has problem when I send an attachment to my bot, it processes wrong JSON and I cannot get URL from it.</p>
  
  <p>I have this code for handling input:</p>
  
  <pre><code>$input = json_decode(file_get_contents('php://input'), true);
  
  file_put_contents('idkResponse.txt', file_get_contents('php://input') . PHP_EOL, FILE_APPEND);
  </code></pre>
  
  <p>And I'm getting all these JSONs</p>
  
  <pre><code>{"object":"page","entry":[{"id":"XXXXX","time":1496729805870,"messaging":[{"sender":{"id":"XXXXX"},"recipient":{"id":"XXXXX"},"timestamp":1496729805429,"message":{"mid":"mid.$XXXXX","seq":1459814,"text":"Hey"}}]}]}
  
  {"object":"page","entry":[{"id":"XXXXX","time":1496729806679,"messaging":[{"sender":{"id":"XXXXX"},"recipient":{"id":"XXXXX"},"timestamp":1496729806556,"message":{"is_echo":true,"app_id":XXXXX,"mid":"mid.$XXXXX","seq":1459815,"text":"Wut?"}}]}]}
  
  {"object":"page","entry":[{"id":"XXXXX","time":1496729806873,"messaging":[{"sender":{"id":"XXXXX"},"recipient":{"id":"XXXXX"},"timestamp":1496729806873,"delivery":{"mids":["mid.$XXXXX"],"watermark":XXXXX,"seq":0}}]}]}
  
  {"object":"page","entry":[{"id":"XXXXX","time":1496729808233,"messaging":[{"sender":{"id":"XXXXX"},"recipient":{"id":"XXXXX"},"timestamp":1496729808232,"read":{"watermark":XXXXX,"seq":0}}]}]}
  </code></pre>
  
  <p>Thank you</p>