#include<bits/stdc++.h>

using namespace std;

ifstram f("patrate3.in");
ofstream g("patrate3.out");

int main(){
    int n,i,count=0;
    long long distntaX,distantaY;
    float x1,y1;
    set<pair<int,int> >set;
    pair<int,int>
    pereche1,pereche2;
    f>>n;
    for(i=0;i<n;++i){
        f>>x1>>y1;
        x1=x1*10000;
        y1=y1*10000;
        set.insert(make_pair(x1,y1));
    }
    for(auto x:set)
        for(auto y:set){
            if(x!=y){
                distantaX=x.second-y.second;
                distantaY=y.first-x.first;
                pereche1=make_pair(distantaX+x.first,distantaY+x.second);
                pereche2=make_pair(distantaX+y.first,distantaY+y.second);
                if(set.find(pereche1)!=set.end() && set.find(pereche2)!=set.end()){
                    ++count;
                }
            }
        }
    g<<count/4;
    return 0;

}