import java.util.Scanner;

 class Main{

public static void main(String[] args) {


Scanner cin=new Scanner(System.in);
while(cin.hasNext()){
double t;
double sum=0.0;
double x1=cin.nextDouble();
double y1=cin.nextDouble();
double x2=cin.nextDouble();
double y2=cin.nextDouble();
double x3=cin.nextDouble();
double y3=cin.nextDouble();
double x4=cin.nextDouble();
double y4=cin.nextDouble();
if(x1>x2){t=x1;x1=x2;x2=t;}
if(y1>y2){t=y1;y1=y2;y2=t;}
if(x3>x4){t=x3;x3=x4;x4=t;}
if(y3>y4){t=y3;y3=y4;y4=t;}
x1=max(x1,x3);
x2=min(x2,x4);
y1=max(y1,y3);
y2=min(y2,y4);
if(x1>x2||y1>y2){
System.out.println("0.00");
}
else{
sum=(x2-x1)*(y2-y1);
System.out.printf("%.2f",sum);
System.out.println();
}

}
}
private static double min(double x2, double x4) {
if(x2<x4)
return x2;
else
return x4;
}
private static double max(double x1, double x3) {
if(x1>x3)
return x1;
else
return x3;
}
}

这个地方要注意的是的判断一下图形是否相交，如果不相交，还是要输出按题目中的输出要求：0.00；不然就会出错，这个题目只有相交和分离两种状态；