#include <fstream>
#include <algorithm>
#include <cmath>
#include <vector>
using namespace std;
ifstream fin("trapez.in");
ofstream fout("trapez.out");
vector <double> v;
const double eps=1.e-14;
const double INF=1.e9;

class POINT 
{
  private: 
  double x,y;
  public:
  POINT()
  {
    x=y=0;
  }
  POINT(double _x, double _y)
  {
    x=_x;
    y=_y;
  }
  POINT(const POINT &other)
  {
    x=other.x;
    y=other.y;
  }
  void set(double _x, double _y)
  {
    x=_x;
    y=_y;
  }
  double getx()
  {
    return x;
  }
  double gety()
  {
    return y;
  }
  
  double dist(const POINT &other)
  {
    return sqrt((x-other.x)*(x-other.x)+(y-other.y)*(y-other.y)); 
  }
  friend double dist(const POINT &p1, const POINT &p2)
  {
    return sqrt((p1.x-p2.x)*(p1.x-p2.x)+(p1.y-p2.y)*(p1.y-p2.y)); 
  }
  POINT mijloc(const POINT &other)
  {
    POINT temp;
    temp.x=(x+other.x)*0.5;
    temp.y=(y+other.y)*0.5;
    return temp;
  }
  double panta(const POINT &other)
  {
    if(fabs(x-other.x)<eps)
      return INF;
    else
      return (y-other.y)/(x-other.x);
  }
};
POINT a[1005];
int main()
{
    int i,n,j,k,z=1,cont=0,l,st,dr;double p,r;bool ok=1;
    long long nr=0;
    POINT temp;
    fin>>n;
    for(i=1;i<=n;i++)
    {
      fin>>j>>k;
      temp.set(j,k);
      a[i]=temp;
    }
    for(i=1;i<=n;i++)
    {
      for(j=i+1;j<=n;j++)
      {
        p=a[i].panta(a[j]);
        v.push_back(p);
      }
    }
    sort(v.begin(),v.end());
    z=v.size();l=1;
    for(i=1;i<z;i++)
    {
     if(fabs(v[i]-v[i-1])<eps)
     l++;
     else
     {nr=nr+1ll*l*(l-1)/2;l=1;}
    }
    nr=nr+1ll*l*(l-1)/2;
    fout<<nr;
    return 0;
}