#include<cstdio>
#include<cmath>
#include<algorithm>

using namespace std;

struct Point
{
    double x,y;
};

int N,sol;
Point P[1005],A,B;

inline bool equals(double A,double B)
{
    if(fabs(A-B)<=0.00001) return 1;
    return 0;
}

inline bool cmp(Point A,Point B)
{
    if(equals(A.x,B.x)) return (A.y<B.y);
    return (A.x<B.x);
}

void determine(Point A,Point &B,Point C,Point &D)
{
    double dx,dy;
    Point M;
    M.x=(A.x+C.x)/2;
    M.y=(A.y+C.y)/2;
    dx=abs(M.x-A.x);
    dy=abs(M.y-A.y);
    if(A.y<C.y)
    {
        B.x=M.x+dy;
        B.y=M.y-dx;
        D.x=M.x-dy;
        D.y=M.y+dx;
    }
    else
    {
        B.x=M.x-dy;
        B.y=M.y-dx;
        D.x=M.x+dy;
        D.y=M.y+dx;
    }
}

bool binary_s(Point A)
{
    int st=1,dr=N,md;
    for(; st<=dr;)
    {
        md=(st+dr)/2;
        if(equals(A.x,P[md].x) && equals(A.y,P[md].y)) return 1;
        if(cmp(A,P[md])) dr=md-1;
        else st=md+1;
    }
    return 0;
}

int main()
{
    int i,j;
    freopen("patrate3.in","r",stdin);
    freopen("patrate3.out","w",stdout);
    scanf("%d",&N);
    for(i=1; i<=N; i++)
        scanf("%lf%lf",&P[i].x,&P[i].y);
    sort(P+1,P+N+1,cmp);
    for(i=1; i<=N; i++)
        for(j=i+1; j<=N; j++)
        {
            determine(P[i],A,P[j],B);
            if(binary_s(A) && binary_s(B)) sol++;
        }
    printf("%d\n",sol/2);
    return 0;
}