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.
输入描述:
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 xi, yi ( - 100 ≤ xi, yi ≤ 100) — the coordinates of the i-th point. It is guaranteed that no two given points coincide.
输出描述:
In the first line print an integer — the number of triangles with the non-zero area among the painted points.
示例1
输入
4<br />0 0<br />1 1<br />2 0<br />2 2<br />3<br />0 0<br />1 1<br />2 0<br />1<br />1 1<br />
备注:
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.
加载中...