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;
}