#include <iostream>
#include <fstream>
#include <algorithm>
#include <cstdio>
#include <utility>
#include <vector>
#include <cmath>
#define x first
#define y second
#define precision 0.001
using namespace std;
ifstream f("triang.in");

class Cmp{
public:
    bool operator()(pair<double,double>A,pair<double,double>B){
        return A.x<B.x;
    }
};

class Triang{
private:
    vector< pair <double,double > > Points;
    int N;
    double modul(double x){
        return (x>0 ? x :-x);
    }
    bool Binary_Search(int poz,pair<double,double>P){
        int st=poz,dr=N,mij;
        while(st<=dr){
            mij=(st+dr)/2;
            if( modul(P.x-Points[mij].x) <= precision && modul(P.y-Points[mij].y) <= precision)return true;
                else
                    if(P.x-Points[mij].x>=precision)dr=mij-1;
                        else
                            st=mij+1;
        }
        return false;
    }
    pair <double,double> NeededPoint( pair<double,double>A,pair<double,double>B,double Sin60,double Cos60){
        return make_pair(A.x+(B.x-A.x)*Cos60-(B.y-A.y)*Sin60,A.y+(B.x-A.x)*Sin60+(B.y-A.y)*Cos60);
    }

public:
    void ReadData(){
        f>>N;
        Points.push_back(make_pair(0,0));
        for(int i=1;i<=N;++i){
            double x,y;
            f>>x>>y;
            Points.push_back( make_pair(x,y) );
        }
        sort(Points.begin()+1,Points.end(),Cmp());
    }
    void GetNumberOfPioints(){
        int Nrt=0;
        for(int i=1;i<=N;i++)
            for(int j=i+1;j<=N;++j){
            Nrt+=Binary_Search(j+1,NeededPoint(Points[i],Points[j],(double)sqrt(3)/2,0.5));
            Nrt+=Binary_Search(j+1,NeededPoint(Points[i],Points[j],-(double)sqrt(3)/2,0.5));
        }
        FILE *fout=fopen("triang.out","w");
        fprintf(fout,"%d",Nrt);
    }
}Ob;

int main()
{
    Ob.ReadData();
    Ob.GetNumberOfPioints();
    return 0;
}