Equal Split Prefixes

You are given an array a of length n.
A split position i is valid if 1 <= i < n and the sum of the first i elements equals the sum of the remaining elements.

Compute the number of valid split positions.

Input
- The first line contains one integer n.
- The second line contains n integers a1, a2, ..., an.

Output
Print the number of valid split positions.

Constraints
- 2 <= n <= 200000
- -10^9 <= ai <= 10^9