A9906. Vanya and Triangles
编程题
普及/提高-
知识点
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.
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 #1
4 0 0 1 1 2 0 2 2
输出 #1
3
输入 #2
3 0 0 1 1 2 0
输出 #2
1
输入 #3
1 1 1
输出 #3
0
说明/提示
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.
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.