#include <bits/stdc++.h> using namespace std; int main() { float a1,a2,b1,b2,c1,c2,d1,d2; cin>>a1>>a2>>b1>>b2>>c1>>c2>>d1>>d2; float yi = max(min(a1,c1),min(c1,a1)); float er = max(min(a2,c2),min(c2,a2)); float san = min(max(b1,d1),max(d1,b1)); float si = min(max(b2,d2),max(d2,b2)); if(b1 == c1 && b2 == c2 && a1 < d1 && a2 < d2) { cout<<setprecision(2)<<fixed<<0.00<<endl; return 0; } cout<<setprecision(2)<<fixed<<(san - yi) * (si - er)<<endl; return 0; }