#include <bits/stdc++.h>
#define x first
#define y second

using namespace std;

using pii = pair<int, int>;

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

const int DIM = 1005;

pii v[DIM], Q[DIM][DIM];
map<pii, int> M; 

int main() {
  int n;
  
  fin >> n;
  for ( int i = 0; i < n; ++i ) {
	fin >> v[i].x >> v[i].y;
	for ( int j = 0; j < i; ++j ) {
	  int d = __gcd(v[i].x - v[j].x, v[i].y - v[j].y);
	  int a = (v[i].x - v[j].x) / d, b = (v[i].y - v[j].y) / d;
	  Q[i][j] = {a, b};
	  ++M[Q[i][j]];
	  ++M[{-a, -b}];
	}
  }
  int res = 0;
  for ( int i = 0; i < n; ++i ) {
    for ( int j = 0; j < i; ++j ) {
	  res += M[Q[i][j]] - 1;
	}
  }
  fout << res / 2;
  fin.close();
  fout.close();
  return 0;
}