#include<stdio.h>
#include<unordered_set>
#include<math.h>
#include<vector>
#include<string>

using namespace std;

class point
{
    public:
    double x,y;
    bool operator==(const point & p2) const
    {
        if(fabs(x-p2.x)<0.0001&&fabs(y-p2.y)<0.0001)return true;
        return false;
    }
};

struct Hash {
  size_t operator()(const point &p) const{
  long long temp = (long long)((p.x+10000)*10000*1000000000+(p.y+10000)*10000);
  return hash<long long>()(temp);
  }
};


vector<point> points;

int n,ras=0;

long long getHash(point p)
{
    return (long long)((p.x+10000)*10000*1000000000+(p.y+10000)*10000);
}

bool cmp(point p1,point p2)
{
    if(fabs(p1.x-p2.x)<0.0001&&fabs(p1.y-p2.y)<0.0001)return true;
    return false;
}
unordered_set<point,Hash> hash_points;

int main()
{
    freopen("patrate3.in","r",stdin);
    freopen("patrate3.out","w",stdout);
    scanf("%d",&n);
    for(int i=0;i<n;++i)
    {
        point p;
        scanf("%lf%lf",&p.x,&p.y);
        hash_points.insert(p);
        points.push_back(p);
    }
    for(int i=0;i<n-1;++i)
        for(int j=i+1;j<n;++j)
        {
            point p1=points[i];point p2=points[j];
            double dy=fabs(p1.y-p2.y)/2;double cy=(p1.y+p2.y)/2;
            double dx=fabs(p1.x-p2.x)/2;double cx=(p1.x+p2.x)/2;
            point p3;p3.x=cx-dy;p3.y=cy-dx;
            point p4;p4.x=cx+dy;p4.y=cy+dx;
            if(hash_points.find(p3)!=hash_points.end()&&hash_points.find(p4)!=hash_points.end())ras++;
        }
    printf("%d\n",ras);

    return 0;
}