Angie is buying a house!

The floor plan of the house can be represented as two rectangles on the Cartesian plane: one from $(x_1,y_1)$ to $(x_2,y_2)$ and one from $(x_3,y_3)$ to $(x_4,y_4)$.

She wants to know how large her house is. Can you help her find out?

Constraints

$1\le x_1,x_2,x_3,x_4,y_1,y_2,y_3,y_4\le {10}^3$

Input Specification

The first line contains the space separated integers $x_1,y_1,x_2,y_2$ (the coordinates of the first rectangle).

The second line contains the space separated integers $x_3,y_3,x_4,y_4$ (the coordinates of the second rectangle).

Output Specification

Output one integer, the total area of the floor plan.

Sample Input

2 6 11 10
14 14 8 5

Sample Output

78