#include <fstream>
#include <vector>
#include <algorithm>
#include <math.h>

using namespace std;

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


const int oo = 2200000000;
const int NMAX = 1005;
vector <double> slopes;
int N;

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

double Slope(punct a, punct b){
  if(a.x - b.x == 0)return oo;
  else
    return (double)(a.y - b.y)/(a.x - b.x);
}

void Read(){
  in >> N;
  for(int i = 1; i <= N; ++i)
    in >> v[i].x >> v[i].y;
}

void Solve(){
  int sol = 0, k = 1;
  for(int i = 1; i <= N; ++i){
    for(int j = i + 1; j <= N; ++j)
      slopes.push_back(Slope(v[i], v[j]));
  }
  sort(slopes.begin(), slopes.end());
  for(int i = 0; i < slopes.size(); ++i){
    if(slopes[i] != oo){
      if(fabs(slopes[i] - slopes[i + 1]) <= 0.00000000001)
        k++;
      else{
        sol += k * (k - 1) / 2;
        k = 1;
      }
    }
  }
  out << sol << "\n";
}

int main(){
  Read();
  Solve();
  return 0;
}