#pragma GCC optimize("O3")
#include <bits/stdc++.h>
#define ll long long
#define rep(i,n) for(int i=0;i<(n);i++)
#define pll pair<ll,ll>
#define pii pair<int,int>
#define pq priority_queue
#define pb push_back
#define eb emplace_back
#define fi first
#define se second
#define endl '\n'
#define ios ios_base::sync_with_stdio(0),cin.tie(0),cout.tie(0);
#define lb(c,x) distance(c.begin(),lower_bound(all(c),x))
#define ub(c,x) distance(c.begin(),upper_bound(all(c),x))

using namespace std;

const ll INF=1e9+10;

int main(){
    ll n;
    cin >> n;
    vector<ll> x(n),y(n);
    rep(i,n){
        cin >> x[i] >> y[i];
    }
    ll sx=x[0],sy=y[0];
    vector<ll> used(n);
    used[0]=1;
    ll ans=0;
    rep(i,n){
        if(used[i]) continue;
        ll ax=abs(x[i]-x[0]),ay=abs(y[i]-y[0]);
        ll ad=ax*ax+ay*ay;
        ll num=-1;
        for(ll j=i+1;j<n;j++){
            if(used[j]) continue;
            ll dx=abs(x[i]-x[j]),dy=abs(y[i]-y[j]);
            ll d=dx*dx+dy*dy;
            if(d<ad){
                ad=d;
                num=j;
            }
        }
        if(num!=-1){
            used[num]=1;
        }
        else{
            ans++;
        }
    }
    cout << ans << endl;
    return 0;
}