#include <fstream>
#include <iomanip>
#include <cmath>
using namespace std;

#define MAX 1005
#define eps 2000000005

ifstream f("trapez.in");
ofstream g("trapez.out");

struct vec
{
    int x,y;
}v[MAX];

double r[MAX*2];
long long N, i , j, nr, cnt, k;

int main()
{
    g << setprecision(14) << fixed;
    f >> N;
    for ( i = 1; i <= N; i++) f >> v[i].x >> v[i].y;

    for ( i = 1; i <= N; i++)
        for ( j = i + 1; j <= N; j++)
            if (v[j].x - v[i].x == 0 && v[j].y - v[i].y == 0) r[++cnt] = eps ;
            else if (v[j].x - v[i].x == 0) r[++cnt] = -eps ;
            else r[++cnt] = (double) (v[j].y - v[i].y) / (v[j].x - v[i].x) ;

    sort( r + 1, r + cnt + 1);
    for ( i = 2; i <= cnt ; i++)
    {
        if (r[i] == r[i-1]) k++;
        else ++k, nr += (k - 1) * k >> 1 , k = 0 ;
        if (r[i] == eps) break;
    }
    if (i == cnt + 1 && r[cnt] != eps) ++k, nr += (k - 1) * k >> 1;
    //for (i=1;i<=N;i++) g << r[i]<<"\n";
    g << nr;
    return 0;
}