#include <fstream>
#include <algorithm>
using namespace std;

ifstream fin("trapez.in");
ofstream fout("trapez.out");

const int MAX = 1010;
const double eli = 0.001;
const int INF = 0x3f3f3f3f;
struct Punct{
    int x, y;
};

Punct p[MAX];
int N;
int nrp, pe;
int nrt;
double pa[MAX * MAX];
double Panta( Punct A, Punct B );

int main()
{
    int i, j;

    fin >> N;
    for ( i = 1; i <= N; i++ )
        fin >> p[i].x >> p[i].y;

    for ( i = 1; i < N; i++ )
        for ( j = i + 1; j <= N; j++ )
        {
            pa[++nrp] = Panta( p[i], p[j] );
        }

   /* for ( i = 1; i <= nrp; i++ )
        fout << pa[i] << ' ';
          fout << '\n'; */
    sort( pa + 1, pa + 1 + nrp );

   /* for ( i = 1; i <= nrp; i++ )
        fout << pa[i] << ' ';
    fout << '\n';   */

    pe = 0;
    for ( i = 1; i < nrp; i++ )
    {
        pe = 0;
        while ( pa[i] == pa[i + 1] )
            i++, pe++;
        nrt += ( pe * ( pe + 1 ) / 2 );
    }

    fout << nrt << '\n';

    fin.close();
    fout.close();
    return 0;
}

double Panta( Punct A, Punct B )
{
    if ( B.x == A.x ) return INF;
    return (double)( B.y - A.y ) / ( B.x - A.x );
}