#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#define _GLIBCXX_DEBUG
using namespace std;
using std::cout;
using std::cin;
using std::endl;
using ll=long long;
using ld=long double;
ll ILL=1167167167167167167;
const int INF=2100000000;
const ll mod=998244353;
#define rep(i,a) for (ll i=0;i<a;i++)
template<class T> using _pq = priority_queue<T, vector<T>, greater<T>>;
template<class T> ll LB(vector<T> &v,T a){return lower_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> ll UB(vector<T> &v,T a){return upper_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> bool chmin(T &a,const T &b){if(a>b){a=b;return 1;}else return 0;}
template<class T> bool chmax(T &a,const T &b){if(a<b){a=b;return 1;}else return 0;}
template<class T> void So(vector<T> &v) {sort(v.begin(),v.end());}
template<class T> void Sore(vector<T> &v) {sort(v.begin(),v.end(),[](T x,T y){return x>y;});}
void yneos(bool a){if(a) cout<<"YES\n"; else cout<<"NO\n";}

ll f(ll a,ll b){
	return a*a+b*b;
}

void solve();
// oddloop
int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	
	int t=1;
	//cin>>t;
	rep(i,t) solve();
}

void solve(){
	int N;
	cin>>N;
	vector<ll> X(N),Y(N);
	rep(i,N) cin>>X[i]>>Y[i];
	vector<tuple<ll,int,int>> p;
	rep(i,N) rep(j,i){
		p.push_back({f(X[i]-X[j],Y[i]-Y[j]),j,i});
	}
	So(p);
	vector<int> q(N,1);
	int ans=0;
	for(auto x:p){
		ll a,b,c;
		tie(c,a,b)=x;
		if(a==0&&q[b]){
			ans++;
			q[b]=0;
		}
		if(a*q[a]*q[b]!=0){
			q[a]=0,q[b]=0;
		}
	}
	cout<<ans<<"\n";
}