1 #include <cstdio>
 2 #include <algorithm>
 3 using namespace std;
 4 
 5 double x1,y1,x2,y2,x3,y3,x4,y4;
 6 double tmp;
 7 
 8 int main()
 9 {
10     while(~scanf("%lf%lf%lf%lf%lf%lf%lf%lf",&x1,&y1,&x2,&y2,&x3,&y3,&x4,&y4)){
11         if(x1>x2){      //使(x1,y1)为左下角点,(x2,y2)为右上角点
12             tmp = x1;
13             x1 = x2;
14             x2 = tmp;
15         }
16         if(y1>y2){
17             tmp = y1;
18             y1 = y2;
19             y2 = tmp;
20         }
21         if(x3>x4){      //使(x3,y3)为左下角点,(x4,y4)为右上角点
22             tmp = x3;
23             x3 = x4;
24             x4 = tmp;
25         }
26         if(y3>y4){
27             tmp = y3;
28             y3 = y4;
29             y4 = tmp;
30         }
31         double length = min(x2,x4)-max(x1,x3);
32         double width = min(y2,y4)-max(y1,y3);
33         printf("%.2f\n",length<0 || width<0 ? 0:length*width);
34     }
35     return 0;
36 }