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

const int MAX_N = 1005;
const double INFINITE = 2e9;
const double EPSILON = 1.e-14;

vector<double> slopes;
pair<int, int> a[MAX_N];

double slope(const pair<int, int> &a, const pair<int, int> &b) {
    if (a.first==b.first) {
        return INFINITE;
    }
    return (1.0 * b.second - a.second) / (1.0 * b.first - a.first);
}

int main() {
    ifstream cin("trapez.in");
    ofstream cout("trapez.out");
    int n;
    cin >> n;
    for (int i = 1; i <= n; ++ i) {
        cin >> a[i].first >> a[i].second;
    }
    for (int i = 1; i <= n; ++ i) {
        for (int j = i + 1; j <= n; ++ j) {
            slopes.push_back(slope(a[i], a[j]));
        }
    }
    sort(slopes.begin(),slopes.end());
    int l = 1;
    int total = 0;
    for (int i = 1; i < (int)slopes.size(); ++ i) {
        if (fabs(slopes[i] - slopes[i - 1]) < EPSILON) {
            ++ l;
        } else {
            total += l * (l - 1) / 2;
            l = 1;
        }
    }
    cout << total << "\n";
    return 0;
}