#include <fstream>
#include <algorithm>
using namespace std;
ifstream fin("trapez.in");
ofstream fout("trapez.out");
bool compare(pair<int, int> a, pair<int, int> b){
    if (a.second == b.second)
        return a.first < b.first;
    return a.second < b.second;
}
int euclid(int a, int b){
    if (b == 0)
        return a;
    int rezultat = euclid(b, a % b);
    return rezultat;
}
pair<int, int> panta(pair<int, int> a, pair<int, int> b){
    pair<int, int> fractie;
    fractie.first = b.second - a.second;
    fractie.second = b.first - a.first;
    int cmmdc = euclid(fractie.first, fractie.second);
    fractie.first /= cmmdc;
    fractie.second /= cmmdc;
    return fractie;
};
int main(){
    pair<int, int> dr[1001];
    pair<int, int> pante[1000001];
    int drepte, contor_pante = 0;
    fin >> drepte;
    for (int i = 1; i <= drepte; i++) {
        fin >> dr[i].first >> dr[i].second;
    }
    for (int i = 1; i < drepte; i++){
        for (int j = i + 1; j <= drepte; j++){
            contor_pante++;
            pante[contor_pante] = panta(dr[i], dr[j]);
        }
    }
    sort(pante+1, pante+1+contor_pante, compare);
    int answer = 0;
    int contor_pante_egale_consecutive = 0;
    for (int i = 1; i <= contor_pante; i++){
        if (pante[i - 1].first == pante[i].first && pante[i-1].second == pante[i].second)
            contor_pante_egale_consecutive++;
        else {
            answer += ((contor_pante_egale_consecutive - 1) * contor_pante_egale_consecutive) / 2;
            contor_pante_egale_consecutive = 1;
        }
    }
    answer += ((contor_pante_egale_consecutive - 1) * contor_pante_egale_consecutive) / 2;
    fout << answer;
    return 0;
}