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 (109 + 7).
输入描述:
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 ai, bi, ci, di(0 ≤ ai, ci ≤ 50; 1 ≤ bi, di ≤ 50; (ai, ci) ≠ (0, 0)). These integers represent a point .No two points coincide.
输出描述:
Print a single integer — the answer to the problem modulo 1000000007(109 + 7).
示例1
输入
10<br />-46 46 0 36<br />0 20 -24 48<br />-50 50 -49 49<br />-20 50 8 40<br />-15 30 14 28<br />4 10 -4 5<br />6 15 8 10<br />-20 50 -3 15<br />4 34 -16 34<br />16 34 2 17<br />10<br />30 30 -26 26<br />0 15 -36 36<br />-28 28 -34 34<br />10 10 0 4<br />-8 20 40 50<br />9 45 12 30<br />6 15 7 35<br />36 45 -8 20<br />-16 34 -4 34<br />4 34 8 17<br />10<br />0 20 38 38<br />-30 30 -13 13<br />-11 11 16 16<br />30 30 0 37<br />6 30 -4 10<br />6 15 12 15<br />-4 5 -10 25<br />-16 20 4 10<br />8 17 -2 17<br />16 34 2 17<br />
加载中...