#include<cstdio>
#include<cmath>
#include<algorithm>
#define eps 1.e-6
using namespace std;
struct POINT
{
    double x,y;
    inline bool operator<(const POINT &other) const
    {
        if(fabs(x-other.x)<eps)
            return y<other.y;
        return x<other.x;
    }
} A,B,p[1010];
int n;
bool searcH(const POINT &t)
{
    int st,dr,med;
    st=1;dr=n;
    while(st<=dr)
    {
        med=(st+dr)/2;
        if(fabs(p[med].x-t.x)<eps && fabs(p[med].y-t.y)<=eps)
            return 1;
        if(t<p[med])
            dr=med-1;
        else
            st=med+1;
    }
    return 0;
}
int main()
{
    freopen("patrate3.in","r",stdin);
    freopen("patrate3.out","w",stdout);
    int res=0;
    scanf("%d",&n);
    for(int i=1;i<=n;i++)
        scanf("%lf%lf",&p[i].x,&p[i].y);
    sort(p+1,p+n+1);
    for(int i=1;i<=n;i++)
        for(int j=i+1;j<=n ;j++)
            {
                A.x=p[i].x+p[i].y-p[j].y;
                A.y=p[i].y+p[j].x-p[i].x;
                B.x=p[i].y+p[j].x-p[j].y;
                B.y=p[j].x+p[j].y-p[i].x;
                if(searcH(A) && searcH(B))
                    res++;
            }
    printf("%d\n",res/2);
    return 0;
}