#include<iostream>
#include<fstream>
#include<functional>
#include<math.h>
#include<set>
#define PI  3.141592653
#define ax imt->first
#define ay imt->second
#define bx jmt->first
#define by jmt->second
using namespace std;
int n, k;
float x, y;
ifstream f("triang.in");
ofstream g("triang.out");
set< pair<float, float>> m;
set< pair<float, float>>::iterator imt, jmt;
pair<float, float> p;
const float eps = 1e-3;
const float si = sin(PI / 3.0);
const float co = cos(PI / 3.0);
int main()
{
    f>>n;
    for(int i=0; i<n; ++i) f>>x>>y, m.insert(make_pair(x, y));

    for(imt=m.begin(); imt!=m.end(); ++imt){
            jmt=imt;++jmt;
    for(; jmt!=m.end(); ++jmt){
        p=make_pair(ax + co*(bx - ax) - si*(by-ay),ay + si*(bx - ax) + co*(by - ay));
       // cout<<p.first<<' '<<p.second<<'\n';
        if(m.find(p)!=m.end()) ++k;
        //else cout<<"nu \n";
        p=make_pair(bx + co*(ax - bx) - si*(ay-by),ay + si*(ax - bx) + co*(ay - by));
       // cout<<p.first<<' '<<p.second<<'\n';
        if(m.find(p)!=m.end())++k;
       // else cout<<"nu \n";
    }
    }


//    for(imt=m.begin(); imt!=m.end(); ++imt)
//    cout<<ax<<' '<<ay<<'\n';
    g<<k;
    return 0;
}