Rectangle Area || LeetCode

#define max(a,b)  ( (a)>(b)?(a):(b) )
#define min(a,b)  ( (a)<(b)?(a):(b) )
int computeArea(int A, int B, int C, int D, int E, int F, int G, int H) {
int downx,downy,upx,upy;
int crossArea;
int all;
downx=max(A,E);
downy=max(B,F);
upx  =min(C,G);
upy  =min(D,H);
if(downx>upx||downy>upy)crossArea=0;
else crossArea=(upx-downx)*(upy-downy);
all=(C-A)*(D-B)+(G-E)*(H-F);
return all-crossArea;
}