I want to get the task Id from the below response.

<?xml version="1.0" encoding="utf-8"?>
<response>
    <task id="56639c84-7f73-4ace-b7ab-a46683ff0e25" registrationTime="2017-06-07T13:46:11Z" statusChangeTime="2017-06-07T13:46:11Z" status="Queued" filesCount="1" credits="10" estimatedProcessingTime="5" />
</response>

Anyone help me how can i get the above task id in apex?