#include <iostream>
#include <vector>
#include <cstdio>
#include <sstream>
#include <map>
#include <string>
#include <algorithm>
#include <queue>
#include <cmath>
#include <set>
using namespace std;

int main(){
	int N;
	cin >> N;
	vector<long long> x(N), y(N);
	for(int i=0; i<N; i++){
		cin >> x[i] >> y[i];
	}
	int ans = 0;
	int bucket_size = 150;
	vector<vector<set< pair<long long,long long> >>> bucket(20000 / bucket_size + 1, vector<set< pair<long long,long long> >>(20000 / bucket_size + 1));
	for(int i=0; i<N; i++){
		int bx = x[i] / bucket_size;
		int by = y[i] / bucket_size;

		bool ok = true;
		for(int dy=max(0,by-1); dy<=min(by+1, 20000 / bucket_size ) && ok; dy++){
			for(int dx=max(0,bx-1); dx<=min(bx+1, 20000 / bucket_size ) && ok; dx++){
				for(auto itr = bucket[dy][dx].begin(); itr != bucket[dy][dx].end() && ok; itr++){
					if( (itr->first - x[i])*(itr->first - x[i]) + (itr->second - y[i])*(itr->second - y[i]) < 20*20 ) ok = false;
				}
			}
		}
		if(ok){
			ans++;
			bucket[by][bx].insert({x[i], y[i]});
		}
	}

	cout << ans << endl;
	return 0;
}