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题库练习 [COCI-2012_2013-contest6]#4 DOBRI
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A1280 | [COCI-2012_2013-contest6]#4 DOBRI

来源COCI
时间限制1s
内存限制128MB
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题目描述

You are given a sequence A consisting of N integers (not to be confused with the sequence from the previous task). We will call the i th sequence 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?

输入格式

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 (-100 000 ≤
Ai ≤ 100 000).

输出格式

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

输入输出样例

输入 #1
2
1 3
输出 #1
1
输入 #2
6
1 2 3 5 7 10
输出 #2
4
输入 #3
3
-1 2 0
输出 #3
1
C++ 编辑器
输入
输出