#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};

const int M=20000;
int n;
set<int> st[M+1];

int main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
	cin>>n;
	vp a;
	int res=0;
	for(int i=-20;i<=20;i++) for(int j=-20;j<=20;j++) if(i*i+j*j<400) a.push_back({i,j});
	for(int i=0;i<n;i++){
		int x,y;
		cin>>x>>y;
		bool B=1;
		for(auto p:a){
			int X=x+p.first,Y=y+p.second;
			if(X<0||X>M||Y<0||Y>M) continue;
			if(st[X].find(Y)!=st[X].end()){
				B=0;
				break;
			}
		}
		if(B) st[x].insert(y),res++;
	}
	cout<<res<<endl;
}