#include <fstream>
#include <map>
#include <algorithm>
#define COS 0.5
#define SIN 0.866025405
#define VAL 1505
#define EPS 0.0001

using namespace std;

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

int N, i, j, ANS;
double X, Y, X1, Y1;
pair <double, double> P[VAL];

double MODUL(double X)
{
    return max(X, -X);
}

int Cautbin(double X, double Y)
{
    int poz=0, i, nr;
    for (i=10; i>=0; i--)
    {
        nr=poz+(1 << i);
        if (nr<=N)
        {
            if (MODUL(P[nr].first-X)<EPS && MODUL(P[nr].second-Y)<EPS)
                return 1;
            if (P[nr].first<X || (P[nr].first==X && P[nr].second<Y))
                poz=nr;
        }
    }
    if (MODUL(P[poz].first-X)<=EPS && MODUL(P[poz].second-Y)<=EPS)
        return 1;
    return 0;
}

int main()
{
    fin >> N;
    for (i=1; i<=N; i++)
        fin >> P[i].first >> P[i].second;
    sort(P+1, P+N+1);
    for (i=1; i<=N; i++)
    {
        for (j=i+1; j<=N; j++)
        {
            X=P[i].first-P[j].first;
            Y=P[i].second-P[j].second;
            X1=X*COS-Y*SIN;
            Y1=X*SIN+Y*COS;
            X1+=P[j].first;
            Y1+=P[j].second;
            ANS+=Cautbin(X1, Y1);

            X=P[j].first-P[i].first;
            Y=P[j].second-P[i].second;
            X1=X*COS-Y*SIN;
            Y1=X*SIN+Y*COS;
            X1+=P[i].first;
            Y1+=P[i].second;
            ANS+=Cautbin(X1, Y1);
        }
    }
    fout << ANS / 2 << '\n';
    fin.close();
    fout.close();
    return 0;
}