#include <fstream>
#include <iostream>
#include <vector>
#include <set>
 
using namespace std;
 
ifstream f("trapez.in");
ofstream g("trapez.out");
 
const int MAX_N = 1005;
const double WHAT = 99999999999LL;
 
int n, rez;
vector <pair <int, int> > Point;
multiset <double> Set;
 
void read() {
    f >> n;
    for (int i = 1; i <= n; i++) {
        int tmp1, tmp2;
        f >> tmp1 >> tmp2;
         
        Point.push_back (make_pair (tmp1, tmp2));
    }
}
 
void solve() {
    double panta;
     
    for (int i = 0; i < n - 1; i++)
        for (int j = i + 1; j < n; j++) {
            if (Point[i].first == Point[j].first)
                panta = WHAT;
            else
                panta = (double)(Point[j].second - Point[i].second) / (double)(Point[j].first - Point[i].first);
            Set.insert (panta);
        }
         
    for (int i = 0; i < n - 1; i++)
        for (int j = i + 1; j < n; j++) {
            if (Point[i].first == Point[j].first)
                panta = WHAT;
            else
                panta = (double)(Point[j].second - Point[i].second) / (double)(Point[j].first - Point[i].first);
			int nr = Set.count (panta);
			rez += nr * (nr - 1) / 2;
			Set.erase (panta);
        }
}
 
int main() {
    read();
    solve();
     
    g << rez << '\n';
     
    f.close();
    g.close();
     
    return 0;
}