AtCoder Regular Contest 173
B
Make Many Triangles
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原题
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Problem Statement

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There are $N$ distinct points on a two-dimensional plane. The coordinates of the $i$-th point are $(x_i,y_i)$.

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We want to create as many (non-degenerate) triangles as possible using these points as the vertices. Here, the same point cannot be used as a vertex of multiple triangles.

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Find the maximum number of triangles that can be created.

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What is a non-degenerate triangle? A non-degenerate triangle is a triangle whose three vertices are not collinear.

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Constraints

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  • $3 \leq N \leq 300$
  • $-10^9 \leq x_i,y_i \leq 10^9$
  • If $i \neq j$, then $(x_i,y_i) \neq (x_j,y_j)$
  • All input values are integers.
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Input

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The input is given from Standard Input in the following format:

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N
x_1 y_1
x_2 y_2
\vdots
x_{N} y_{N}

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Output

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Print the answer.

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样例

Input #1
7
0 0
1 1
0 3
5 2
3 4
2 0
2 2
Output #1
2
For example, if we create a triangle from the first, third, and sixth points and another from the second, fourth, and fifth points, we can create two triangles. The same point cannot be used as a vertex for multiple triangles, but the triangles may have overlapping areas.
Input #2
3
0 0
0 1000000000
0 -1000000000
Output #2
0
题目信息
题号
arc173_b
时间限制
2 s
内存限制
1024 MB

题面与样例版权归 AtCoder 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。