#include <iostream>
#include <fstream>
#include <map>
using namespace std;

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

map <double, int> panta;

struct punct{
  int x;
  int y;
};
punct v[1000];

int main() {
  int n, i, j, nr, s;
  fin >> n;
  for( i = 0; i < n; i++ )
    fin >> v[i].x >> v[i].y;
  s = nr = 0;
  for( i = 0; i < n; i++ ) {
    for( j = i + 1; j < n; j++ ) {
      if( v[j].x == v[i].x )
        s++;
      else {
        nr += panta[(double)( v[j].y - v[i].y )/( v[j].x - v[i].x )];
        panta[(double)( v[j].y - v[i].y )/( v[j].x - v[i].x )]++;
      }
    }
  }
  fout << nr + s * ( s - 1 ) / 2;
  return 0;
}