1 #include <iostream>
2 #include <cstdio>
3
4 using namespace std;
5
6 struct line
7 {
8 double x1;
9 double y1;
10 double x2;
11 double y2;
12 }l[110];
13
14 bool test(int i,int j)
15 {
16 int s=0;
17 double acd = (l[j].x1-l[i].x1)*(l[j].y1-l[j].y2) - (l[j].x1-l[j].x2)*(l[j].y1-l[i].y1);
18 double bcd = (l[j].x1-l[i].x2)*(l[j].y1-l[j].y2) - (l[j].x1-l[j].x2)*(l[j].y1-l[i].y2);
19 if(acd*bcd<=0)
20 s++;
21 double abd = (l[i].x1-l[j].x1)*(l[i].y1-l[i].y2) - (l[i].x1-l[i].x2)*(l[i].y1-l[j].y1);
22 double abc = (l[i].x1-l[j].x2)*(l[i].y1-l[i].y2) - (l[i].x1-l[i].x2)*(l[i].y1-l[j].y2);
23 if(abd*abc<=0)
24 s++;
25 if(s==2)
26 return true;
27 return false;
28 }
29
30 int main()
31 {
32 int n;
33 while(scanf("%d",&n)!=EOF)
34 {
35 if(n==0)
36 break;
37 for(int i=0;i<n;i++)
38 {
39 scanf("%lf%lf%lf%lf",&l[i].x1,&l[i].y1,&l[i].x2,&l[i].y2);
40 }
41 int ans=0;
42 for(int i=0;i<n-1;i++)
43 {
44 for(int t=i+1;t<n;t++)
45 {
46 if(test(i,t))
47 ans++;
48 }
49 }
50 cout<<ans<<endl;
51 }
52 return 0;
53 }
