#include <bits/stdc++.h>
#define DIM 1005

using namespace std;

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

int n;
pair <int, int> points[DIM];
map <double, int> fr;

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

    for (int i = 1; i <= n; i++)
        for (int j = i + 1; j <= n; j++)
        {
            double m = (double)(points[i].first - points[j].first) / (points[i].second - points[j].second);
            fr[m] += 1;
        }

    long long ans = 0;
    for (auto k: fr)
        ans += k.second * (k.second - 1) / 2;

    g << ans;
    return 0;
}