Bob the penguin is part of a special species of penguins that can fly! He has recently discovered a peculiar fact: all the icebergs (even the floating ones!!) that he and his fellow flying penguin inhabit can be modelled as rectangles! In particular, Bob the penguin is examining a single iceberg with coordinates ~(x_1,y_1), (x_2,y_2), (x_3,y_3), (x_4,y_4)~, in clockwise order of vertices, starting from the top left. He would like to know the area of the iceberg that is located above the x-axis, or in other words, the area of the region above the line ~y=0~. However, since Bob the penguin isn't able to program this problem with his flippers, he asks you to help code this problem!

Input Specification

There will be ~4~ lines of input, with the ~i^{th}~ line containing two space-separated integers ~x_i, y_i~.

Output Specification

Output one integer, representing the total area of the iceberg that is located above the x-axis.

Constraints

For all subtasks, ~-10^3 \leq x_i \leq 10^3~

Subtask 1 [50%]

All coordinates have a non-negative ~y~ value, where ~0 \leq y_i \leq 10^3~.

Subtask 2 [50%]

~-10^3 \leq y_i \leq 10^3~

Sample Input

-3 2
7 2
7 -6
-3 -6

Sample Output

20

Sample Explanation

As observed in the graph, the portion above the x-axis has width ~10~ and height ~2~.