Tracing last part of instance name

Hi, Iam wondering if someone can help me.
I have different movieclips on the stage and named the instances “item_0”, “item_1”, “item_2” etc.

I want to trace in actionscript only the number of the movieclips and put that in a variable at the moment there is CLICK event. I need only the number because Iam trying to link the number with a XML file.

Does anyone know how to adress only a specific, in this case the last, part of the instancename.