#include <iostream>
#include <fstream>
#include <map>
#include <cmath>
#include <vector>
using namespace std;
ifstream f("patrate3.in");
ofstream g("patrate3.out");

map <pair<int,int>,int> h;
vector <pair<int,int>> v;

int n, rez, x, y;

float xx, yy;

int main()
{
    f >> n;
    for(int i = 1; i <= n; i ++)
    {
        f >> xx >> yy;
        x = (int)round(xx*10000);
        y = (int)round(yy*10000);
        v.push_back(make_pair(x,y));
        h[make_pair(x,y)] = 1;
    }
    for(int i = 0; i < n; i ++)
        for(int j = 0; j < n; j ++) {
            if(i == j)
                continue;
            int dx = v[i].first - v[j].first;
            int dy = v[j].second - v[i].second;
            if(h.find(make_pair(v[i].first + dy, v[i].second + dx)) == h.end())
                continue;
            if(h.find(make_pair(v[j].first + dy, v[j].second + dx)) == h.end())
                continue;
            rez ++;
        }
    rez /= 4;
    g << rez;
    return 0;
}