cycles get inverted zmask??

Hey all just wondering if anyone knows a way to get equivalent of the zmask but with the inverted checked of in the compositor for cycles. Cycles dosn’t have the invert option on the mask layers. Node setup to achieve ?

Ok, finally found a workflow so here it is for the cycles users that do compositing and such.
Make three render layers; 1 main, 2 with your mask layer checked off, and 3 same as 2 but no mask layers.
Next in compositor subtract 2 Alpha from 3 Alpha and finally you have a mask of only what’s in layer 2 behind layer 1.