int x1,y1,x2,y2,x3,y3,x4,y4;
	
	cin>>x1>>y1>>x2>>y2>>x3>>y3>>x4>>y4;

	int X1, Y1, X2, Y2, X3, Y3, X4, Y4;

	X1=min(x1,x2);
	X2=max(x1,x2);
	Y1=min(y1,y2);
	Y2=max(y1,y2);


	X3=min(x3,x4);
	X4=max(x3,x4);
	Y3=min(y3,y4);
	Y4=max(y3,y4);
	
	int left=max(X1,X3);
	int right=min(X2,X4);
	int bottom=max(Y1,Y3);
	int top=min(Y2,Y4);

	if(right>left && top>bottom)
		cout<<(right-left)*(top-bottom)<<endl;
	else
		cout<<0<<endl;
	return 0;
}