#include <iostream>
#include <algorithm>
#include <fstream>
using namespace std;
ifstream f("patrate3.in");
ofstream g("patrate3.out");
struct punct
{
    double x,y;
};
punct a[1001],mx,my,p3,p4;
int n,nr;
const double EPS=0.0001;
double modul(double x,double y)
{
    if(x>y)
    {
        return x-y;
    }
    else
    {
        return y-x;
    }
}
inline bool cmp(const punct a,const punct b)
{
    if(a.x==b.x)
    {
        return a.y<b.y;
    }
    else
    {
        return a.x<b.x;
    }
}
bool cautare_binara(punct p)
{
    int st,dr,mij;
    st=1;
    dr=n;
    while(st<=dr)
    {
        mij=(st+dr)/2;
        if(modul(a[mij].x,p.x)<EPS && modul(a[mij].y,p.y)<EPS)
        {
            return 1;
        }
        else
        {
            if(modul(a[mij].x,p.x)<EPS)
            {
                if(p.y>a[mij].y)
                {
                    st=mij+1;
                }
                else
                {
                    dr=mij-1;
                }
            }
            else
            {
                if(p.x>a[mij].x)
                {
                    st=mij+1;
                }
                else
                {
                    dr=mij-1;
                }
            }
        }
    }
    return 0;
}
int main()
{
    int i,j;
    double distx,disty,mx,my;
    f>>n;
    for(i=1;i<=n;i++)
    {
        f>>a[i].x>>a[i].y;
    }
    sort(a+1,a+n+1,cmp);
    for(i=1;i<n;i++)
    {
        for(j=i+1;j<=n;j++)
        {
            mx=(a[i].x+a[j].x)/2;
            my=(a[i].y+a[j].y)/2;
            distx=modul(a[i].x,mx);
            disty=modul(a[i].y,my);
            if(a[i].y<a[j].y)
            {
                p3.x=mx+disty;
                p3.y=my-distx;
                p4.x=mx-disty;
                p4.y=my+distx;
            }
            else
            {
                p3.x=mx-disty;
                p3.y=my-distx;
                p4.x=mx+disty;
                p4.y=my+distx;
            }
            nr=nr+cautare_binara(p3)*cautare_binara(p4);
        }
    }
    g<<nr/2;
    return 0;
}