var
   x1, y1, x2, y2, x3, y3, x4, y4, xx1, xx2, yy1, yy2, x, y, t1, t2, kek, kek1: integer;
begin
   readln(x1, y1, x2, y2, x3, y3, x4, y4);
   if (y1 > y2) then
   begin
      yy1 := y1;
       t1 := y2;
   end
   else
   begin
      yy1 := y2;
       t1 := y1;
   end;
   if (y3 > y4) then
   begin
      yy2 := y3;
       t2 := y4;
   end
   else
   begin
      yy2 := y4;
       t2 := y3;
   end;
   if (((yy2 > yy1) and (t2 >= yy1)) or ((yy1 > yy2) and (t1 >= yy2))) then
      kek := 0
   else
      kek := 1;

   if (x1 > x2) then
   begin
      xx1 := x1;
       t1 := x2;
   end
   else
   begin
      xx1 := x2;
       t1 := x1;
   end;
   if (x3 > x4) then
   begin
      xx2 := x3;
       t2 := x4;
   end
   else begin
      xx2 := x4;
       t2 := x3;
   end;
   if (((xx2 > xx1) and (t2 >= xx1)) or ((xx1 > xx2) and (t1 >= xx2))) then
      kek1 := 0
   else
      kek1 := 1;
//проверка пересечения окончена
   if (abs(x4 - x2) >= abs(x3 - x1)) then
      x := abs(x3 - x1)
   else
      x := abs(x4 - x2);
   if (abs(y3 - y2) >= abs(y4 - y1)) then
      y := abs(y4-y1)
   else
      y :=abs(y3 - y2);
   if ((kek + kek1 = 0) or ((kek1 <> 0) and (kek = 0)) or ((kek1 <> 0) and (kek = 0))) then
      writeln('0')
   else
      writeln(x*y);
   readln;
end.