计算 矩形重叠面积

#include <cstdio>
#include <cmath>
#include <algorithm>

using namespace std;

int main()
{
double x[4],y[4];
while (scanf("%lf%lf",&x[0],&y[0])!=-1){
for (int i=1;i<=3;i++) scanf("%lf%lf",&x[i],&y[i]);
if (max(x[0],x[1])<min(x[2],x[3]) || min(x[0],x[1])>max(x[2],x[3]) || max(y[0],y[1])<min(y[2],y[3]) || min(y[0],y[1])>max(y[2],y[3])) printf("0.00\n");

else{
sort(x,x+4); sort(y,y+4);
printf("%.2lf\n",abs(x[1]-x[2])*abs(y[1]-y[2]));
}
}
}