← 返回题目
题库练习 [COCI-2007_2008-contest2]#4 PRAVOKUTNI
← 上一题 下一题 →

A1110 | [COCI-2007_2008-contest2]#4 PRAVOKUTNI

来源COCI
时间限制1s
内存限制128MB
通过 / 提交0/0

题目描述

N points are placed in the coordinate plane.
Write a program which calculates in how many ways a right triangle can be formed by three of the given points. A right triangle is one in which one of the angles is 90 degrees.

输入格式

The first line of input contains an integer N (3 ≤ N ≤ 1500), the number of points.
Each of the following N lines contains the coordinates of one point, two integers separated by a space.
The coordinates will be between −109 and 10
9.
No two points will be located at the same coordinates.

输出格式

Output the number of right triangles.

输入输出样例

输入 #1
3 
4 2 
2 1 
1 3
输出 #1
1
输入 #2
4 
5 0 
2 6 
8 6 
5 7
输出 #2
0
输入 #3
5 
-1 1 
-1 0 
0 0 
1 0 
1 1
输出 #3
7
C++ 编辑器
输入
输出