#include <algorithm>
#include <iostream>
#include <fstream>
#include <map>

#define INF 1000000

using namespace std;

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

int sol , nr , n , x = 1;

double panta[1000005];

pair <double , double> a[1005];

int main() {
    f >> n;

    for(int i = 1 ; i <= n ; ++i) {
        f >> a[i].first >> a[i].second;
    }

    for(int i = 1 ; i <= n ; ++i) {
        for(int j = i + 1 ; j <= n ; ++j) {
            if(a[j].second == a[i].second) {
                panta[++nr] = INF;
            }
            else {
                panta[++nr] = (a[j].first - a[i].first) / (a[j].second - a[i].second);
            }
        }
    }

    sort(panta + 1 , panta + nr + 1);

    for(int i = 2 ; i <= nr ; ++i) {
        if(panta[i] == panta[i - 1]) {
            ++x;
        }

        else {
            sol = sol + x * (x - 1) / 2;
            x = 1;
        }
    }

    sol = sol +  x * (x - 1) / 2;

    g << sol;
    return 0;
}