#include <bits/stdc++.h>
#define Nmax 1001
#define eps 10000
using namespace std;
ifstream f("patrate3.in");
ofstream g("patrate3.out");
pair <int,int> pct[Nmax];
#define x first
#define y second
int main()
{
    int n,i,j;
    f>>n;
    double x,y;
    for(i=1;i<=n;i++)
    {
        f>>x>>y;
        pct[i].x=2*round(x*eps);
        pct[i].y=2*round(y*eps);
    }
    sort(pct+1,pct+n+1);
    int mx,my,dx,dy;
    int ans=0;
    for(i=1;i<n;i++)
        for(j=i+1;j<=n;j++)
        {
            mx=(pct[i].x+pct[j].x)/2;
            my=(pct[i].y+pct[j].y)/2;
            dx=mx-pct[i].x;
            dy=my-pct[i].y;
            if(binary_search(pct+1,pct+n+1,make_pair(mx-dy,my+dx)))
                if(binary_search(pct+1,pct+n+1,make_pair(mx+dy,my-dx)))
                    ++ans;
        }
    g<<ans/2;

    return 0;
}