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A9363. Drawing Circles is Fun

编程题 普及/提高-

题目描述

There are a set of points $S$ on the plane. This set doesn't contain the origin $O(0,0)$ , and for each two distinct points in the set $A$ and $B$ , the triangle $OAB$ has strictly positive area.

Consider a set of pairs of points $(P_{1},P_{2}),(P_{3},P_{4}),...,(P_{2k-1},P_{2k})$ . We'll call the set good if and only if:

- $k>=2$ .
- All $P_{i}$ are distinct, and each $P_{i}$ is an element of $S$ .
- For any two pairs $(P_{2i-1},P_{2i})$ and $(P_{2j-1},P_{2j})$ , the circumcircles of triangles $OP_{2i-1}P_{2j-1}$ and $OP_{2i}P_{2j}$ have a single common point, and the circumcircle of triangles $OP_{2i-1}P_{2j}$ and $OP_{2i}P_{2j-1}$ have a single common point.

Calculate the number of good sets of pairs modulo $1000000007$ $(10^{9}+7)$ .

输入格式

The first line contains a single integer $n$ $(1<=n<=1000)$ — the number of points in $S$ . Each of the next $n$ lines contains four integers $a_{i},b_{i},c_{i},d_{i}$ $(0<=|a_{i}|,|c_{i}|<=50; 1<=b_{i},d_{i}<=50; (a_{i},c_{i})≠(0,0))$ . These integers represent a point ![](/uploads/acgo/image/c222aff44d2fe495_dc85c71cdcb2.jpeg).

No two points coincide.

输出格式

Print a single integer — the answer to the problem modulo $1000000007$ $(10^{9}+7)$ .

输入输出样例

输入 #1
10
-46 46 0 36
0 20 -24 48
-50 50 -49 49
-20 50 8 40
-15 30 14 28
4 10 -4 5
6 15 8 10
-20 50 -3 15
4 34 -16 34
16 34 2 17
输出 #1
2
输入 #2
10
30 30 -26 26
0 15 -36 36
-28 28 -34 34
10 10 0 4
-8 20 40 50
9 45 12 30
6 15 7 35
36 45 -8 20
-16 34 -4 34
4 34 8 17
输出 #2
4
输入 #3
10
0 20 38 38
-30 30 -13 13
-11 11 16 16
30 30 0 37
6 30 -4 10
6 15 12 15
-4 5 -10 25
-16 20 4 10
8 17 -2 17
16 34 2 17
输出 #3
10
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