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

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

struct pct{
    int y,x;
};

struct panta{
    int index1, index2;
    int dy, dx;
};

int abs(int x){
    if(x<0) return -x;
    return x;
}

int comparPante(panta a, panta b){
    long long produs1 = (long long) a.dx * b.dy;
    long long produs2 = (long long) b.dx * a.dy;

    return produs1 > produs2;
}

bool panteEgale(panta a, panta b){
    long long produs1 = (long long) a.dx * b.dy;
    long long produs2 = (long long) b.dx * a.dy;

    return produs1 == produs2;
}

const int N = 1000;
panta pante[N*N];
pct puncte[N];
int n,nPante;

int main()
{



    in>>n;
    for(int i=0; i<n; ++i)
        in>>puncte[i].x>>puncte[i].y;

    nPante = 0;
    for(int i=0; i<n; ++i)
        for(int j=i+1; j<n; ++j){
            pante[nPante].index1 = i;
            pante[nPante].index2 = j;
            pante[nPante].dx = (puncte[i].x - puncte[j].x);
            pante[nPante].dy = (puncte[i].y - puncte[j].y);
            ++nPante;
        }

    ///for(int i=0; i<nPante; ++i) cout<<pante[i].index1<<" "<<pante[i].index2<<" "<<(1.0 * pante[i].dy / pante[i].dx)<<"\n"; cout<<"\n";

    sort(pante, pante+nPante, comparPante);

    ///for(int i=0; i<nPante; ++i) cout<<pante[i].index1<<" "<<pante[i].index2<<" "<<(1.0 * pante[i].dy / pante[i].dx)<<"\n"; cout<<"\n";

    int cntPanteEgale = 1;
    int cntTrapeze = 0;
    for(int i=1; i<nPante; ++i)
    {
        bool panteleSuntEgale = panteEgale(pante[i-1], pante[i]);
        if(panteleSuntEgale)
            ++cntPanteEgale;

        if(!panteleSuntEgale || i == nPante-1){
            cntTrapeze += cntPanteEgale * (cntPanteEgale-1) / 2;
            cntPanteEgale = 1;
        }
    }
    out<<cntTrapeze;

    return 0;
}