Codeforces Round 308 (Div. 2)
D
Vanya and Triangles
Codeforces
1900
原题
← CE →
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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.

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Input

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The first line contains integer $*n*$ ($1 ≤ *n* ≤ 2000$) — the number of the points painted on the plane.

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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.

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Output

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

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Note

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Note to the first sample test. There are $3$ triangles formed: $(0, 0) - (1, 1) - (2, 0)$; $(0, 0) - (2, 2) - (2, 0)$; $(1, 1) - (2, 2) - (2, 0)$.

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Note to the second sample test. There is $1$ triangle formed: $(0, 0) - (1, 1) - (2, 0)$.

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Note to the third sample test. A single point doesn't form a single triangle.

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样例

Input #1
4
0 0
1 1
2 0
2 2
Output #1
3
InputCopy OutputCopy
Input #2
3
0 0
1 1
2 0
Output #2
1
InputCopy OutputCopy
Input #3
1
1 1
Output #3
0
InputCopy OutputCopy
题目信息
题号
552D
时间限制
4 s
内存限制
512 MB
标签
暴力
组合数学
数据结构
计算几何
数学
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