//Deresu Roberto - FMI
//Re :)
#include<fstream>
#include<algorithm>
#include<cstring>
#include<map>
using namespace std;
int n,rez;
char sir[11];

struct punct
{
    double x,y;
}a[1007];

map<double,double>mymap;

ifstream fin("patrate3.in");
ofstream fout("patrate3.out");

int cmp(punct a, punct b)
{
    if(a.x < b.x || (a.x == b.x && a.y < b.y)) return 1;
    return 0;
}

int cauta(double x, double y)
{
    map<double,double> :: iterator it = mymap.find(x);

    while(it != mymap.end() && it->first == x)
    {
        if(it->second == y)return 1;
        it++;
    }

    return 0;
}

double numar()
{
    int i;
    double x, semn;

    i = 0;
    x = 0.0;
    semn = 1.0;

    if(sir[0] == '-') semn = -1.0, i++;

    while(sir[i] != '.') x = x*10+sir[i++]-'0';
    i++;
    while(sir[i])
     x = x*10+sir[i++]-'0';

    return semn*x*10;
}

int main()
{
    fin>>n;

    for(int i=1;i<=n;i++)
    {
        //fin>>sir;
        //a[i].x = numar();
        //fin>>sir;
        //a[i].y = numar();
        fin>>a[i].x>>a[i].y;
        mymap.insert(make_pair(a[i].x,a[i].y));
    }

    sort(a+1,a+n+1,cmp);

    for(int i=1;i<n;i++)
        for(int j=i+1;j<=n;j++)
        {
            double x3,y3,x4,y4,mijx,mijy,dx,dy;

            mijx = (a[i].x+a[j].x)/2;
            mijy = (a[i].y+a[j].y)/2;
            dx = mijx - a[i].x;
            dy = mijy - a[i].y;

            if(a[i].y < a[j].y)
            {
                x3 = mijx+dy;
                y3 = mijy-dx;
                x4 = mijx-dy;
                y4 = mijy+dx;

                if(cauta(x3,y3) && cauta(x4,y4)) rez++;
            }
            else
            {
                x3 = mijx-dy;
                y3 = mijy-dx;
                x4 = mijx+dy;
                y4 = mijy+dx;

                if(cauta(x3,y3) && cauta(x4,y4)) rez++;
            }
        }

    fout<<rez;

	return 0;
}