#include <fstream>
#include <algorithm>
using namespace std;

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

const int N = 1005;

int n, sol, k;
pair <int, int> v[N];
double p[N*N];

int main() {
    fin >> n;
    for (int i = 0; i < n; ++i)
        fin >> v[i].first >> v[i].second;
    sort (v, v + n);
    for (int i = 0; i < n - 1; ++i)
        for (int j = i + 1; j < n; ++j) {
            int x = v[j].first - v[i].first, y = v[j].second - v[i].second;
            p[k++] = (double) x / (double) y;
        }
    sort (p, p + k);
    int egal = 0, nr = 0;
    for (int i = 1; i < k && p[i] < (double) 1 / (double) 0; ++i) {
        nr = i;
        if (abs (p[i] - p[i-1]) < 1e-9)
            egal++;
        else {
            sol += (egal * (egal + 1)) >> 1;
            egal = 0;
        }
    }
    sol += (egal * (egal + 1)) >> 1;
    if (nr != k - 1) {
        egal = (k - nr - 2);
        sol += (egal * (egal + 1)) >> 1;
    }
    fout << sol;
}