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Time Limit: 4.0 s Memory Limit: 32 MB Total points: 80

#17107. 直角三角形

Statistics

在坐标平面上放置了 $N$ 个点。

编写一个程序,计算由给定的点中的三个点可以组成多少个直角三角形。直角三角形是指其中一个角为 $90$ 度的三角形。

输入格式

输入的第一行包含一个整数 $N$ ($3 \le N \le 1500$),表示点的数量。

接下来的 $N$ 行,每行包含一个点的坐标,为两个由空格隔开的整数。坐标的范围在 $-10^9$ 到 $10^9$ 之间。

任意两个点不会位于相同的坐标。

输出格式

输出直角三角形的数量。

样例

输入样例 1

3
4 2
2 1
1 3

输出样例 1

1

输入样例 2

4
5 0
2 6
8 6
5 7

输出样例 2

0

输入样例 3

5
-1 1
-1 0
0 0
1 0
1 1

输出样例 3

7

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