# Use C + + to complete the magic array applet

2022-01-27 01:16:55

Title Description ：
There is a circular wide array , On the circumference of the circular normal matrix N A little bit , When four different points on the circumference of the normal matrix can just form a rectangle , Normal array can produce 1 Unit energy .（ If Zhizhi has a different node , It is considered that the two rectangles are different , The same point can be counted into multiple rectangles .）
Now? , It is known that the arc length between two adjacent points is a positive integer , The arc length between two adjacent points is given in the order starting from a certain point , Find out how much unit energy this normal array can produce .
Input format ：
The first line is an integer N
Next N That's ok , One integer per row , Respectively represent the arc length divided between two adjacent points .
Output format ：
An integer , Represents the energy generated by the normal array .
sample input ：
8
1
2
2
3
1
1
3
3

sample output ：
3
Data range and tips ：
about 40％ The data of , Satisfy N<=20
about 70％ The data of , Satisfy N<=5000
about 100％ The data of , Satisfy N<=200000

Hint , If you want to be rectangular , His diagonal must pass through the center of the circle , That is to say, it must be a half circle from the starting point to the diagonal point .