#include <iostream>
#include<fstream>
#include<algorithm>
#include<vector>
#include<cmath>
#define mod 666013
#define Nmax 1001
#define k 10000
using namespace std;
int n,sol;
double x,y;
vector <int> hash[mod];
struct punct
{
    int x,y;
};
punct puncte[Nmax];
punct rotatie(punct X,punct Y)
{
    X.x-=Y.x;
    X.y-=Y.y;

    int aux;
    aux=X.x;
    X.x=X.y;
    X.y=aux;

    X.x=-X.x;
    X.x+=Y.x;
    X.y+=Y.y;

    return X;

}
int find(punct A)
{
    int code=1LL*A.x*A.y%mod;
    if(code<0)
        code+=mod;
    int lg=hash[code].size();

    for(int i=0;i<lg;++i)
    {
        if(A.x == puncte[hash[code][i]].x && A.y==puncte[hash[code][i]].y)
            return 1;
    }
    return 0;
}
void frac(int &val)
{
    if(val>=0)
    {
        if(val%10==9)
            val=val/10+1;
        else
            val/=10;
    }
    else
    {
        if(-val%10==9)
            val=val/10-1;
        else
            val/=10;
    }
}
void citire()
{
    int i;
    ifstream fin("patrate3.in");
    fin>>n;
    for(i=1;i<=n;++i)
    {
        fin>>x>>y;
        x*=100000;
        y*=100000;
        puncte[i].x=x;
        puncte[i].y=y;
        frac(puncte[i].x);
        frac(puncte[i].y);

        int code=1LL * puncte[i].x*puncte[i].y % mod;
        if(code<0)
            code+=mod;
        hash[code].push_back(i);
    }

}
void solve()
{
    int i,j;
    punct mij,p1,p2;
    for(i=1;i<n;++i)
    {
        for(j=i+1;j<=n;++j)
        {
            mij.x=(puncte[i].x + puncte[j].x)/2;
            mij.y=(puncte[i].y + puncte[j].y)/2;
            p1=rotatie(puncte[i], mij);
            p2=rotatie(puncte[j],mij);
            if(find(p1) && find(p2))
                sol++;
        }
    }
    ofstream fout("patrate3.out");
    fout<<sol/2<<"\n";
    fout.close();
}
int main()
{
    citire();
    solve();
    return 0;
}