#include <fstream>
#include <cmath>
#include <algorithm>
using namespace std;

#define Dif 0.0000000001

struct coord
{
    double x,y;
}v[1010];

int n,i,j,nr;

bool compar(coord a, coord b)
{
    if( fabs(a.x-b.x)<=Dif )
        return a.y<b.y;
    else
        return a.x<b.x;
}

int cautare(coord a)
{
    int l,r,mij;
    l=1;
    r=n;
    while(l<=r)
    {
        mij=(l+r)/2;
        if (fabs(v[mij].x-a.x)<=Dif&&fabs(v[mij].y-a.y)<=Dif)
            return 1;
        else
        if (compar(a,v[mij]))
            r=mij-1;
        else
        l=mij+1;
    }
    return 0;
}


int main()
{

    ifstream in("patrate3.in");
    ofstream out("patrate3.out");
    in>>n;
    for(i=1;i<=n;i++)
        in>>v[i].x>>v[i].y;
    sort(v+1,v+n+1,compar);
    nr=0;
    for(i=1;i<n;i++)
        for(j=i+1;j<=n;j++)
        {
            coord a,b;
            a.x = v[i].x + v[i].y - v[j].y;
            b.x = v[j].x + v[i].y - v[j].y;
            a.y = v[i].y + v[j].x - v[i].x;
            b.y = v[j].y + v[j].x - v[i].x;
            if(cautare(a)&&cautare(b))
                nr++;
        }
    out<<nr/2;
    return 0;
}