How to reach xml data with dependency item?

[Gutsycat]

I have this xml

<root>
<device id="id of device 1">
<parameter id="1">6</parameter>
<parameter id="2">5</parameter>
</device>
<device id="id of device 2">
<parameter id="1">7</parameter>
<parameter id="2">8</parameter>
</device>
<device id="id of device 3">
<parameter id="1">9</parameter>
<parameter id="2">10</parameter>
<parameter id="3">5</parameter>
</device>
<device id= "id of device 4">
<parameter id="1">11</parameter>
<parameter id="2">12</parameter>
</device>
</root>

In zabbix I have master item(for "loading xml") and lot's of dependent to retrieve parameters.

What should I write in key of dependent item to retrieve value from ex. id of device3 -> parameter id="2"?