#include <iostream>
using namespace std;
int main()
{
    int x1,x2,x3,x4,y1,y2,y3,y4,xq,yq,xx,yx,s=0;
    cin>>x1>>y1>>x2>>y2;
    cin>>x3>>y3>>x4>>y4;
    xq=max(min(x1,x2),min(x3,x4));
    xx=min(max(x1,x2),max(x3,x4));
    yq=max(min(y1,y2),min(y3,y4));
    yx=min(max(y1,y2),max(y3,y4));
    if ((xx-xq>0) && (yx-yq>0)) s=(xx-xq)*(yx-yq);
    cout<<s;
}