Stripe 2

题意翻译

### 题目大意 给出一个长度为 $n$ 的序列，问有多少种方案将序列划分为恰好连续的三段（每个元素都属于某一段），使得每一段的和都相等。 ### 输入输出格式 输入格式 第一行：一个整数 $n$ 第二行：$n$个整数，表示序列 输出格式 第一行：一个整数表示方案数

题目描述

Once Bob took a paper stripe of n squares (the height of the stripe is 1 square). In each square he wrote an integer number, possibly negative. He became interested in how many ways exist to cut this stripe into three pieces so that the sum of numbers from each piece is equal to the sum of numbers from any other piece, and each piece contains positive integer amount of squares. Would you help Bob solve this problem?

输入输出格式

输入格式

The first input line contains integer $ n $ ( $ 1<=n<=10^{5} $ ) — amount of squares in the stripe. The second line contains n space-separated numbers — they are the numbers written in the squares of the stripe. These numbers are integer and do not exceed 10000 in absolute value.

输出格式

Output the amount of ways to cut the stripe into three non-empty pieces so that the sum of numbers from each piece is equal to the sum of numbers from any other piece. Don't forget that it's allowed to cut the stripe along the squares' borders only.

输入输出样例

输入样例 #1

4
1 2 3 3

输出样例 #1

1

输入样例 #2

5
1 2 3 4 5

输出样例 #2

0