#include <bits/stdc++.h>
using namespace std;
int dist(int x1,int y1,int x2,int y2){
	return (x1-x2)*(x1-x2)+(y1-y2)*(y1-y2);
}
int main(){
	int n;	cin>>n;
	vector<int> x(n),y(n);
	for(int i=0;i<n;i++)	cin>>x[i]>>y[i];
	set<pair<int,int>> grd;
	int cnt=0;
	for(int i=0;i<n;i++){
		auto it=grd.lower_bound(make_pair(x[i]-20,y[i]-20));
		if(it==grd.end()){
			grd.insert(make_pair(x[i],y[i]));
			cnt++;
		}
		else{
			bool canput=true;
			while(it!=grd.end()&&it->first<=x[i]+20){
				if(dist(x[i],y[i],it->first,it->second)<400){
					canput=false;
					break;
				}
				if(y[i]+20<it->second){
					it=grd.lower_bound(make_pair(it->first+1,y[i]-20));
				}
				else it=grd.lower_bound(make_pair(it->first,it->second+1));
			}
			if(canput){
				grd.insert(make_pair(x[i],y[i]));
				cnt++;
			}
		}
	}
	cout<<cnt<<endl;
	return 0;
}