#include<cstdio>
#include<vector>
#include<algorithm>

#define NMAX 1005
#define INF 0x3f3f3f3f

FILE *f=fopen("trapez.in","r");
FILE *g=fopen("trapez.out","w");

using namespace std;


int n,Answer;
vector <double> slope;

struct point {
   int x,y;
}v[NMAX];

void Read( void )
{
 fscanf(f,"%d",&n);
 for( int i(1) ; i <= n ; ++i )
 {
    fscanf(f,"%d%d",&v[i].x,&v[i].y);
 }
  fclose(f);
}

inline double Incline ( const point A , const point B )
{
    if(A.x != B.x )
   return ((double) B.y-A.y)/(B.x-A.x);
      else
        return INF;
}

void Solve ( void )
{
    for( int i(1) ; i <= n ; ++i )
    {
        for(int ii(i+1) ; ii <= n ; ++ii )
            slope.push_back(Incline(v[i],v[ii]));
    }
    sort(slope.begin(),slope.end());

   for( vector<double>::iterator it=slope.begin() ; it!=slope.end() ;  )
   {
      double  val=*it;
       int ccount=0;
       ++it;
       while( val == *it && it!=slope.end())
        ++ccount,++it;
        Answer+=ccount *( ccount-1 )/2;

   }

}
void Write ( void )
{
  fprintf(g,"%d",Answer);
  fclose(g);
}
int main ( void )
{
    Read();
    Solve();
    Write();
    return 0;
}