Discrete Math- tree

In a variant of a mesh network for interconnecting n = m^2 processors, processor P(i, j) is connected to the four processors P((i plusorminus 1) mod m, j) and P(i, (j plusorminus 1 mod m), so that connections wrap around the edges of the mesh. Draw this variant of the mesh network for 16 processors. Draw a parsing tree for (a - (3 + 2b))/(c^2 + d)