#include <iostream>
#include<cmath>
#include<algorithm>
using namespace std;
int main()
{
double x[4],y[4];
    double s,l,h;
while(cin>>x[0]>>y[0]>>x[1]>>y[1]>>x[2]>>y[2]>>x[3]>>y[3])
{
l=fabs(x[1]-x[0])+fabs(x[3]-x[2]);
h=fabs(y[1]-y[0])+fabs(y[3]-y[2]);
sort(x,x+4);
sort(y,y+4);
l=l-x[3]+x[0];
h=h-y[3]+y[0];
s=l*h;
if(l<=0||h<=0) s=0;
printf("%.2lf\n",s);


}
return 0;
}