#include <bits/stdc++.h>
#define syosu(x) fixed<<setprecision(x)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> P;
typedef pair<double,double> pdd;
typedef pair<ll,ll> pll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<double> vd;
typedef vector<vd> vvd;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<string> vs;
typedef vector<P> vp;
typedef vector<vp> vvp;
typedef vector<pll> vpll;
typedef pair<int,P> pip;
typedef vector<pip> vip;
const int inf=1<<30;
const ll INF=1ll<<60;
const double pi=acos(-1);
const double eps=1e-8;
const ll mod=1e9+7;
const int dx[4]={-1,0,1,0},dy[4]={0,-1,0,1};

int n;

int main(){
	cin>>n;
	set<P> st;
	for(int i=0;i<n;i++){
		int x,y;
		cin>>x>>y;
		bool B=1;
		for(int X=x-20;X<=x+20;X++) for(int Y=y-20;Y<=y+20;Y++){
			int d=(x-X)*(x-X)+(y-Y)*(y-Y);
			if(d<400&&st.find({X,Y})!=st.end()) B=0;
		}
		if(B) st.insert({x,y});
	}
	cout<<st.size()<<endl;
}