#include<bits/stdc++.h>
using namespace std;
#define int long long
#define REP(i,m,n) for(int i=(m);i<(n);i++)
#define rep(i,n) REP(i,0,n)
#define pb push_back
#define all(a) a.begin(),a.end()
#define rall(c) (c).rbegin(),(c).rend()
#define mp make_pair
#define endl '\n'
#define vec vector<ll>
#define mat vector<vector<ll> >
#define fi first
#define se second
typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll,ll> pll;
typedef long double ld;
typedef complex<double> comp;
const ll INF=1e9+7;
const ll inf=INF*INF;
const ll MOD=1e9+7;
const ll mod=MOD;
const int MAX=200010;



signed main(){
    ll n;cin>>n;
    vector<ll>x(n),y(n);
    rep(i,n){
        cin>>x[i]>>y[i];
    }
    vector<pair<ll,pll> >d(0);
    rep(i,n){
        REP(j,i+1,n){
            pair<ll,pll>p;
            p.fi=(x[i]-x[j])*(x[i]-x[j])+(y[i]-y[j])*(y[i]-y[j]);
            p.se.fi=i;
            p.se.se=j;
            d.pb(p);
        }
    }
    sort(all(d));
    set<ll>st;
    ll ans=0;
    rep(i,d.size()){
        ll x=d[i].se.fi;
        ll y=d[i].se.se;
        if(st.find(x)==st.end()){
            if(st.find(y)==st.end()){
                if(x!=0)st.insert(x);
                if(y!=0)st.insert(y);
                if(x==0)ans++;
                if(y==0)ans++;
            }else{
                continue;
            }
        }else{
            continue;
        }
    }
    cout<<ans<<endl;
}