#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(a1,c1); float er = max(a2,c2); float san = min(b1,d1); float si = min(b2,d2); cout<<setprecision(2)<<fixed<<(san - yi) * (si - er); return 0; }