400548: GYM100203 G Good elements

You are given a sequence A consisting of N integers. We will call the i-th element good if it equals the sum of some three elements in positions strictly smaller than i (an element can be used more than once in the sum).

How many good elements does the sequence contain?

The first line of input contains the positive integer N (1 ≤ N ≤ 5000), the length of the sequence A.

The second line of input contains N space-separated integers representing the sequence A ( - 10⁵ ≤ A_i ≤ 10⁵).

The first and only line of output must contain the number of good elements in the sequence.

2
1 3

1

6
1 2 3 5 7 10

4

3
-1 2 0

1