hdu2056

#include<iostream>
#include<cstdio>
#include<iomanip>
using namespace std;
class point
{
public:
    double x, y;
} p[9];
int main()
{
    while(cin >> p[1].x >> p[1].y >> p[2].x >> p[2].y >> p[3].x >> p[3].y >> p[4].x >> p[4].y)
    {
        double temp;
        for(int i = 1; i <= 4; i += 2)
        {
            if(p[i].x > p[i+1].x)
            {
                temp = p[i].x;
                p[i].x = p[i+1].x;
                p[i+1].x = temp;
            }
            if(p[i].y > p[i+1].y)
            {
                temp = p[i].y;
                p[i].y = p[i+1].y;
                p[i+1].y = temp;
            }
        }
        double s;
        if(p[2].x<=p[3].x ||p[2].y<=p[3].y ||p[4].x<=p[1].x||p[4].y<=p[1].y)
        {
            cout << "0.00" << endl;
        }
        else
        {
            double a = p[1].x > p[3].x ? p[1].x : p[3].x;
            double b = p[2].x < p[4].x ? p[2].x : p[4].x;
            double c = p[1].y > p[3].y ? p[1].y : p[3].y;
            double d = p[2].y < p[4].y ? p[2].y : p[4].y;
            s = (b-a)*(d-c);
            cout << fixed << setprecision(2) << s << endl;
        }
    }
}