#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<cctype>
#include<cstdlib>
#include<algorithm>
#include<bitset>
#include<vector>
#include<list>
#include<deque>
#include<queue>
#include<map>
#include<set>
#include<stack>
#include<cmath>
#include<sstream>
#include<fstream>
#include<iomanip>
#include<ctime>
#include<complex>
#include<functional>
#include<climits>
#include<cassert>
#include<iterator>
using namespace std;

int n;
set<int> s[20010];
int dist(int a, int b, int c, int d){
	if (a < c){
		swap(a, c);
	}
	if (b < d){
		swap(b, d);
	}
	return (a - c)*(a - c) + (b - d)*(b - d);
}
int main(){
	scanf("%d", &n);
	set<int>::iterator ite;
	int countt = 0;
	for (int i = 0; i < n; i++){
		int x, y;
		scanf("%d%d", &x, &y);
		int mint = max(0, x - 19);
		int maxt = x + 19;
		bool ok = false;
		for (int j = mint; j <= maxt; j++){
			if (s[j].size() == 0){
				continue;
			}
			ite = s[j].lower_bound(y);
			if (ite != s[j].end()){
				if (dist(x,y,j,(*ite)) < 400){
					ok = true;
					break;
				}
			}
			if (ite != s[j].begin()){
				ite--;
				if (dist(x,y,j,(*ite)) < 400){
					ok = true;
					break;
				}
			}
		}
		if (ok == false){
			s[x].insert(y);
			countt++;
		}
	}
	printf("%d\n", countt);
	return 0;
}