#include<bits/stdc++.h>
#define rep(i, n) for(int i = 0; i < (int)(n); i++)
using namespace std;
typedef long long ll;
typedef pair<int,int> P;
int INF = (1LL << 30) - 1;
int MOD = 1e9+7;
main(){
    int N;
    cin >> N;
    vector< P > V(N);
    vector<set<int> > X(20010);
    rep(i,N){
        int a,b;
        cin >> a >> b;
        V[i] = P(a,b);
    }
    int cnt = 0;
    rep(i,N){
        auto p = V[i];
        int x = p.first, y = p.second;
        bool ok = 1;
        //(x,y)との距離の2乗が400未満となる点を探す
        for(int j = max(0,x-20);j <= x+20;j++){
            for(int k = max(0,y-20);k <= y+20;k++){
                ll r = (x - j) * (x - j) + (y - k) * (y - k);
                //cout << j << " " << k << endl;
                if(X[j].count(k) && r < 400){
                    ok = 0;
                    j = x+20;
                    break;
                }
            }
        }
        if(ok){
            X[x].insert(y);
            cnt++;
        }
    }
    cout << cnt << endl;
}