1 #include <iostream>
 2 #include <cstring>
 3 #include <algorithm>
 4 #include <cstdio>
 5 using namespace std;
 6 const int Max = 110;
 7 const double eps = 0.000001;
 8 struct Point
 9 {
10     double x, y;
11     Point(double x = 0, double y = 0) : x(x), y(y) {}
12 };
13 struct Line
14 {
15     Point start, End;
16 };
17 Line line[Max];
18 typedef Point Vector;
19 Vector operator- (Vector A, Vector B)
20 {
21     return Vector(A.x - B.x, A.y - B.y);
22 }
23 double Cross(Vector A, Vector B)
24 {
25     return A.x * B.y - A.y * B.x;
26 }
27 bool OnSegment(Point A, Point B, Point C)
28 {
29     double MinX, MaxX, MinY, MaxY;
30     if (A.x - B.x > eps)
31     {
32         MinX = B.x;
33         MaxX = A.x;
34     }
35     else
36     {
37         MinX = A.x;
38         MaxX = B.x;
39     }
40     if (A.y - B.y > eps)
41     {
42         MinY = B.y;
43         MaxY = A.y;
44     }
45     else
46     {
47         MinY = A.y;
48         MaxY = B.y;
49     }
50     // 大于等于 >=  -eps
51     if (C.x - MinX >= -eps && MaxX - C.x >= -eps && C.y - MinY >= -eps && MaxY - C.y >= -eps)
52         return true;
53     return false;
54 }
55 bool solve(Line A, Line B)
56 {
57     double c1 = Cross(A.End - A.start, B.start - A.start);
58     double c2 = Cross(A.End - A.start, B.End - A.start);
59     double c3 = Cross(B.End - B.start, A.start - B.start);
60     double c4 = Cross(B.End - B.start, A.End - B.start);
61     if (c1 * c2 < 0 && c3 * c4 < 0)  // && 手残写成了 || wa了好几次
62         return true;
63     if (c1 == 0 && OnSegment(A.start, A.End, B.start))
64         return true;
65     if (c2 == 0 && OnSegment(A.start, A.End, B.End))
66         return true;
67     if (c3 == 0 && OnSegment(B.start, B.End, A.start))
68         return true;
69     if (c4 == 0 && OnSegment(B.start, B.End, A.End))
70         return true;
71     return false;
72 }
73
74 int main()
75 {
76     int n;
77     while (scanf("%d", &n) != EOF && n)
78     {
79         int res = 0;
80         for (int i = 1; i <= n; i++)
81         {
82             scanf("%lf%lf%lf%lf", &line[i].start.x, &line[i].start.y, &line[i].End.x, &line[i].End.y);
83         }
84         for (int i = 1; i <= n; i++)
85         {
86             for (int j = i + 1; j <= n; j++)
87             {
88                 if (solve(line[i], line[j]))
89                     res++;
90             }
91         }
92         printf("%d\n", res);
93     }
94     return 0;
95 }