#include <cstdio>
#include <cmath>
#include <algorithm>

using namespace std;

const double eps = 1.e-14;
const double INF = 2.e9;

 struct POINT{
   double x, y;
 }v[1005];


bool vertical(POINT a, POINT b){
  return fabs(a.x - b.x) < eps;
}

double panta(POINT a, POINT b){
  if(vertical(a, b)){
    return INF;
  }
  else
    return (b.y - a.y) / (b.x - a.x);
}

double p[1000005];

int main()
{
    freopen("trapez.in", "r", stdin);
    freopen("trapez.out", "w", stdout);
    int n, i, j, k, nr;
    scanf("%d", &n);
    for(i = 0;i < n;i++){
      scanf("%lf%lf", &v[i].x, &v[i].y);
    }
    k = 0;
    for(i = 0;i < n;i++){
      for(j = i + 1;j < n;j++){
        p[k] = panta(v[i], v[j]);
        k++;
      }
    }
    sort(p, p + k);
    j = 1;
    nr = 0;
    for(i = 1;i < k;i++){
      if(fabs(p[i] - p[i - 1]) > eps){
        nr += j * (j - 1) / 2;
        j = 0;
      }
      j++;
    }
    printf("%d", nr);
    return 0;
}