#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;
double slope[500010];

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 INF;
		else
   return (double)( B.y-A.y)/(B.x-A.x);
      
}

void Solve ( void )
{
	int numb(0);
    for( int i(1) ; i <= n ; ++i )
    {
        for(int ii(i+1) ; ii <= n ; ++ii )
            slope[++numb]=Incline(v[i],v[ii]);
    }
    sort(slope+1,slope+numb+1);
    int i;
   for( i=1 ; i <= numb;   )
   {
       int start=i;
       int ccount=0;
       ++i;
       while( slope[start] == slope[i] && i <= numb)
	   ++ccount,++i;
       Answer+=ccount *( ccount-1 )/2;

   }

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