hi guys, i need desperate help please!

I have a slab, measuring 12.3m by 6.2m, with footings 750mm deep and 500m wide. The trench mesh is laid on the perimeter of the slab, and comes in 6m lengths. It also has to overlap at the corners and , where two sheets meet, there must be 500mm of overlap. I need to calculate the lengths of mesh required, if it requires two layers of mesh, but I am so confused. I have drawn a diagram, but i just cant seem to figure it out.Could someone PLEASE help me? thank you.