#include <fstream>

using namespace std;

ifstream cin("trapez.in");
ofstream cout("trapez.out");

struct punct
{
    float x, y;
};
short n;
int i, j, k, t, r;
punct p[1001];
double m[500501];

void qsort(double v[], int st, int dr)
{
      int i=st, j=dr;
      double piv = v[(st+dr)/2];
      while (i <= j)
      {
            while (v[i] < piv) i++;
            while (v[j] > piv) j--;
            if (i <= j)
            {
                  swap(v[i],v[j]);
                  i++;
                  j--;
            }
      }
      if (st < j) qsort(v, st, j);
      if (i < dr) qsort(v, i, dr);
}
int main()
{
    cin>>n;
    for(i=1; i<=n; i++) cin>>p[i].x>>p[i].y;
    k=0;
    for(i=1; i<n; i++)
        for(j=i+1; j<=n; j++)
            if(p[i].x==p[j].x) r++;
            else m[++k]=(p[i].y-p[j].y)/(p[i].x-p[j].x);
    t+=r*(r-1)/2;
    qsort(m, 1, k);
    r=1;
    for(i=2; i<=k; i++)
        if(m[i]==m[i-1]) r++;
        else
        {
            t+=r*(r-1)/2;
            r=1;
        }
    t+=r*(r-1)/2;
    cout<<t;
    return 0;
}