Vanya and Triangles

题意翻译

求平面上n个点中三个点两两相连形成面积不为0的三角形的个数.

题目描述

Vanya got bored and he painted $ n $ distinct points on the plane. After that he connected all the points pairwise and saw that as a result many triangles were formed with vertices in the painted points. He asks you to count the number of the formed triangles with the non-zero area.

输入输出格式

输入格式

The first line contains integer $ n $ ( $ 1<=n<=2000 $ ) — the number of the points painted on the plane. Next $ n $ lines contain two integers each $ x_{i},y_{i} $ ( $ -100<=x_{i},y_{i}<=100 $ ) — the coordinates of the $ i $ -th point. It is guaranteed that no two given points coincide.

输出格式

In the first line print an integer — the number of triangles with the non-zero area among the painted points.

输入输出样例

输入样例 #1

4
0 0
1 1
2 0
2 2

输出样例 #1

3

输入样例 #2

3
0 0
1 1
2 0

输出样例 #2

1

输入样例 #3

1
1 1

输出样例 #3

0

说明

Note to the first sample test. There are $ 3 $ triangles formed: $ (0,0)-(1,1)-(2,0) $ ; $ (0,0)-(2,2)-(2,0) $ ; $ (1,1)-(2,2)-(2,0) $ . Note to the second sample test. There is $ 1 $ triangle formed: $ (0,0)-(1,1)-(2,0) $ . Note to the third sample test. A single point doesn't form a single triangle.