#include<fstream>
#include<iostream>
#include<vector>
#include<algorithm>
#define EPS 1e-12
#define oo 2000001050.0
using namespace std;

vector<pair<int, int>> point;
vector<double> p;

int main() {
    int n, x, y, a, j;
    long long cnt;
    ifstream fin("trapez.in");
    ofstream fout("trapez.out");
    fin >> n;
    for(int i = 0; i < n; ++i) {
        fin >> x >> y;
        point.emplace_back(make_pair(x, y));
    }
    fin.close();
    for(unsigned i = 0; i < point.size(); ++i) {
        for(unsigned j = i + 1; j < point.size(); ++j)
            if(point[i].first == point[j].first)
                p.emplace_back(oo);
            else p.emplace_back((double)(point[i].second - point[j].second) / (double)(point[i].first - point[j].first));
    }
    sort(p.begin(), p.end());
    int i = 0;
    cnt = 0;
    while(i < n) {
        j = i + 1;
        while(j < n && (p[j] - p[j - 1]) < EPS)
            ++j;
        a = j - i;
        i = j;
        cnt += (a * (long long)(a - 1)) / 2LL;
    }
    fout << cnt << "\n";
    fout.close();
    return 0;
}