  We give a new combinatorial proof of the well known result that the dinv of
an $(m,n)$-Dyck path is equal to the area of its sweep map image. The first
proof of this remarkable identity for co-prime $(m,n)$ is due to Loehr and
Warrington. There is also a second proof (in the co-prime case) due to Gorsky
and Mazin and a third proof due to Mazin.
