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