#include <fstream>
#include <set>
#include <cmath>
#include <vector>

#define fn "patrate3."
using namespace std;
ifstream f(fn"in");
ofstream g(fn"out");
int main() {
    set<pair<int,int>> vec;
    vector<pair<int,int>> per;
    int n;
    float x,y;
    f>>n;
    for(int i = 0 ; i < n ; ++i )
    {
        f>>x>>y;
        per.push_back({round(x*10000),round(y*10000)});
        vec.insert(per[i]);
    }
    int nr=0,x1,y1,x2,y2;
    for(int i = 0 ; i < n ; ++i)
        for(int j = 0 ; j < n ; ++j){
            if(i!=j) {
                x1 = per[i].second - per[j].second + per[j].first;
                y1 = per[j].first - per[i].first + per[j].second;
                x2 = per[i].second - per[j].second + per[i].first;
                y2 = per[j].first - per[i].first + per[i].second;
                    if(vec.find({x1,y1})!= vec.end())
                        if(vec.find({x2,y2})!=vec.end() )
                            nr++;
            }
        }
    g<<floor(sqrt(nr));

    return 0;
}