1 #include <iostream>
 2 #include <stdio.h>
 3 #include <string.h>
 4 #include <stack>
 5 #include <queue>
 6 #include <map>
 7 #include <set>
 8 #include <vector>
 9 #include <math.h>
10 #include <algorithm>
11 using namespace std;
12 const double pi = acos(-1.0);
13 const int INF = 0x3f3f3f3f;
14 
15 struct Line
16 {
17     double x1,y1,x2,y2;
18 }node[105];
19 
20 bool solve(Line a, Line b)//叉积判断两线段是否相交
21 {
22     if (((a.x1-b.x1)*(a.y2-b.y1)-(a.x2-b.x1)*(a.y1-b.y1))*((a.x1-b.x2)*(a.y2-b.y2)-(a.x2-b.x2)*(a.y1-b.y2))>0)
23     return false;
24     if (((b.x1-a.x1)*(b.y2-a.y1)-(b.x2-a.x1)*(b.y1-a.y1))*((b.x1-a.x2)*(b.y2-a.y2)-(b.x2-a.x2)*(b.y1-a.y2))>0)
25     return false;
26     return true;
27 }
28 
29 int main ()
30 {
31     int n;
32     while (scanf ("%d",&n),n)
33     {
34         for (int i=0; i<n; i++)
35         scanf ("%lf%lf%lf%lf",&node[i].x1,&node[i].y1,&node[i].x2,&node[i].y2);
36         int cnt = 0;
37         for (int i=0; i<n; i++)
38         {
39             for (int j=i+1; j<n; j++)
40             {
41                 if (solve(node[i], node[j]))
42                 cnt++;
43             }
44         }
45         printf ("%d\n",cnt);
46     }
47     return 0;
48 }