#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
#define Nmax 1005
#define e 0.00001
using namespace std;
int n,i,j;
double c,d;
int sol;
struct nod
{
    double x;
    double y;
}v[Nmax],a,b,m;
int cb(nod a)
{
    int st=1,dr=n,mij=0;
    while (st<=dr)
    {
        mij=(st+dr)/2;
        if (abs(v[mij].x-a.x)<=e && abs(v[mij].y-a.y)<=e) return 1;
        if (abs(v[mij].x-a.x)<=e && v[mij].y<a.y) st=mij+1;
        else if (abs(v[mij].x-a.x)<=e) dr=mij-1;
        else if (v[mij].x<a.x) st=mij+1;
        else dr=mij-1;
    }
    return 0;
}
int cmp(const nod a,const nod b)
{
    if (a.x==b.x) return a.y<b.y;
    return a.x<b.x;
}
int main()
{
    freopen("patrate3.in","r",stdin);
    freopen("patrate3.out","w",stdout);
    scanf("%d",&n);
    for (i=1;i<=n;i++)
    scanf("%lf %lf",&v[i].x,&v[i].y);
    sort(v+1,v+n+1,cmp);
    for (i=1;i<=n;i++)
    for (j=i+1;j<=n;j++)
    {
        m.x=(v[i].x+v[j].x)/2;
        m.y=(v[i].y+v[j].y)/2;
        c=abs(m.x-v[i].x);
        d=abs(m.y-v[i].y);
        if (v[i].y>v[j].y)
        {
            a.x=m.x-d;
            a.y=m.y-c;
            b.x=m.x+d;
            b.y=m.y+c;
            if (cb(a)&&cb(b)) ++sol;
        } else
        {
            a.x=m.x+d;
            a.y=m.y-c;
            b.x=m.x-d;
            b.y=m.y+c;
            if (cb(a)&&cb(b)) ++sol;
        }
    }
    printf("%d",sol/2);
    return 0;
}