#include<fstream>
#include<algorithm>
#define eps 0.0001
#define x first
#define y second
using namespace std;
int n, i, j, sol;
double difx, dify;
pair<double, double> v[1005], mid;
ifstream fin("patrate3.in");
ofstream fout("patrate3.out");
double modul(double x){
    if(x > 0){
        return x;
    }
    return -x;
}
int egal(double a, double b){
    if(modul(a - b) < eps){
        return 1;
    }
    return 0;
}
double cautbin(double xc, double yc){
    int st = 1, dr = n, mid;
    while(st <= dr){
        mid = (st + dr) / 2;
        if(egal(xc, v[mid].x) && egal(yc, v[mid].y)){
            return 1;
        }
        if((egal(xc, v[mid].x) && v[mid].y < yc) || v[mid].x < xc){
            st = mid + 1;
        }
        else{
            dr = mid - 1;
        }
    }
    return 0;
}
int main(){
    fin>> n;
    for(i = 1; i <= n; i++){
        fin>> v[i].x >> v[i].y;
    }
    sort(v + 1, v + n + 1);
    for(i = 1; i < n; i++){
        for(j = i + 1; j <= n; j++){
            mid.x = (v[i].x + v[j].x) / 2;
            mid.y = (v[i].y + v[j].y) / 2;
            difx = mid.x - v[i].x;
            dify = mid.y - v[i].y;
            if(cautbin(mid.x - dify, mid.y + difx) == 1 && cautbin(mid.x + dify, mid.y - difx) == 1){
                sol++;
            }
        }
    }
    fout<< sol / 2 <<"\n";
    return 0;
}