#include <stdio.h>
#include <math.h>
#include <map>
using namespace std;

#define nmax 1024

struct par
{
    double x,y;
};
map<par,int> H;
int n,i,j,sol;
par a,b,c,d,v[nmax];

float round(float x)
{
    if (x-floor(x)>ceil(x)-x)
        return ceil(x);
    return floor(x);
}

bool operator < (const par &A, const par &B)
{
    if (A.x != B.x)
        return A.x < B.x;
    return A.y < B.y;
}

int main()
{
    freopen("patrate3.in","r",stdin);
    freopen("patrate3.out","w",stdout);

    scanf("%d\n",&n);
    for (i=0;i<n;i++)
    {
        scanf("%lf %lf\n",&v[i].x,&v[i].y);
        v[i].x*=10000;
        v[i].y*=10000;
        v[i].x=round(v[i].x);
        v[i].y=round(v[i].y);
        H[v[i]]=1;
    }
    for (i=0;i<n;i++)
        for (j=i+1;j<n;j++)
        {
            a=v[i],b=v[j];
            c.x=b.x+a.y-b.y,c.y=b.y+b.x-a.x;
            d.x=a.y+a.x-b.y,d.y=b.x+a.y-a.x;
            if ((H[c]==1)&&(H[d]==1))
                ++sol;
        }
    printf("%d\n",sol/2);

    return 0;
}