#include <iostream>
#include <fstream>
#include <tr1/unordered_set>
#include <algorithm>
#include <cmath>
#define x first
#define y second

using namespace std;

const double EPS = 1e-6;
const double cos60 = 0.5, sin60 = 0.5 * sqrt (3);
const double PI = 3.1415926535897932384626433832795;

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

typedef pair <double, double> point;

struct hasher
{
    int operator () (const point &A) const
    {
        int ret = A.x * PI + A.y;
        return ret;
    }
};

struct point_equal
{
    bool operator () (const point &A, const point &B) const
    {
        return abs (A.x - B.x) <= EPS && abs (A.y - B.y) <= EPS;
    }
};

point P[1510];
tr1 :: unordered_set <point, hasher, point_equal> M;

struct comp
{
    inline bool operator () (const point &A, const point &B) const
    {
        if (abs (A.x - A.y) <= EPS)
            return A.y - B.y <= -EPS;

        return A.x - B.x <= -EPS;
    }
};

point get (const point &A, const point &B)
{
    point now, ret;

    now.x = B.x - A.x;
    now.y = B.y - A.y;
    ret.x = now.x * cos60 - now.y * sin60;
    ret.y = now.x * sin60 + now.y * cos60;
    ret.x += A.x;
    ret.y += A.y;

    return ret;
}

int main()
{
    int N, i, j, Ans = 0;
    point now;

    in >> N;
    for (i = 1; i <= N; i ++)
        in >> P[i].x >> P[i].y;

    sort (P + 1, P + N + 1, comp ());

    for (i = 1; i <= N; i ++){
        for (j = 1; j < i; j ++){
            now = get (P[i], P[j]);

            if (M.count (now))
                Ans ++;
        }

        M.insert (P[i]);
    }

    out << Ans;

    return 0;
}