#include <iostream>
#include <fstream>
#include <cmath>
#include <set>
#include <algorithm>
#include <iomanip>

#define PI 3.14159265

const int MAXN = 1e4 + 5;

using namespace std;

ifstream in("triang.in");
ofstream out("triang.out");

typedef long double ld;

pair<ld,ld> v[MAXN];
int n;

int cautbinar(ld x,ld y){
    int pas = 1<<10, r = 0;
    while(pas){
        if(r + pas <= n && (v[r + pas].first < x || (abs(v[r + pas].first - x) <= 1e-3 && abs(y - v[r + pas].second) <= 1e-3))){
            r += pas;
        }
        pas /= 2;
    }
    return r;
}


int main()
{
    in>>n;
    for(int i = 1; i <= n; i++){
        ld x,y;
        in>>x>>y;
        v[i] = {x,y};
    }
    sort(v + 1,v + n + 1);

    int ans = 0;
    for(int i = 1; i <= n; i++){
        for(int j = i + 1; j <= n; j++){
            ld difx = v[j].first - v[i].first;
            ld dify = v[j].second - v[i].second;
            ld unghi = PI / 3;
            ld rotx = difx * cos(unghi) - dify * sin(unghi);
            ld roty = difx * sin(unghi) + dify * cos(unghi);
            ld x = v[i].first + rotx,y = v[i].second + roty;

            int index = cautbinar(x,y);
            pair<ld,ld>gasit = v[index];
            if(j < index && abs(gasit.first - x) < 1e-3 && abs(gasit.second - y) < 1e-3){
                ans++;
            }
            unghi = - PI / 3;
            rotx = difx * cos(unghi) - dify * sin(unghi);
            roty = difx * sin(unghi) + dify * cos(unghi);
            x = v[i].first + rotx,y = v[i].second + roty;
            index = cautbinar(x,y);
            gasit = v[index];
            if(j < index && abs(gasit.first - x) < 1e-3 && abs(gasit.second - y) < 1e-3){
                ans++;
            }

        }
    }
    out<<ans;
    return 0;
}