#include<cstdio>
#include<algorithm>
#include<vector>
struct punct{int x,y;};
punct v[1001];
double pante[1000001];
long long drepte,trapeze;
int n;
int modul(int a)
{
 if(a<0)
    return a*-1;
 else
    return a;
}
using namespace std;
int main()
{
 freopen("trapez.in","r",stdin);
 freopen("trapez.out","w",stdout);
 scanf("%d ",&n);
 for(int i=1;i<=n;i++)
     {
      scanf("%d %d ",&v[i].x,&v[i].y);
     }
 for(int i=1;i<=n;i++)
     {
      for(int j=i+1;j<=n;j++)
          {
           drepte++;
           pante[drepte]=1.0*(v[j].y-v[i].y)/(v[j].x-v[i].x);
          }
     }
 sort(pante+1,pante+drepte+1);
 for(int i=1;i<=drepte;i++)
     {
      int paralele=1;
      while(pante[i]==pante[i+1] && i+1<=drepte)
            {
             i++;
             paralele++;
            }
      trapeze+=paralele*(paralele-1)/2;
     }
 printf("%lld",trapeze);
return 0;
}