#include"bits/stdc++.h"

//#include<bits/stdc++.h>
using namespace std;
#define print(x) cout<<x<<endl;
#define rep(i,a,b) for(int i=a;i<b;i++)
#define REP(i,a) for(int i=0;i<a;i++)
typedef long long ll;
typedef pair<int, int> PI;
typedef pair<int, PI> V;
typedef vector<int> VE;
const ll mod = 100000000000;

int n, x[100002], y[100002];
bool now[100002];
VE center[20100];
int main() {
	cin >> n;
	bool flag = 1;
	int count = 0;
	REP(i, n)cin >> x[i] >> y[i];
	REP(i, n) {
		int xl = max(0, x[i] - 20);
		int xr = x[i] + 20;
		flag = 1;
		for (int nx = xl; nx <= xr; nx++) {
			for (auto ny : center[nx]) {
				ll dist = pow(x[i] - nx, 2) + pow(y[i] - ny, 2);
				if (dist < 400) {
					flag = 0;
					break;
				}
			}
		}
		if (flag) {
			count++;
			center[x[i]].push_back(y[i]);
		}
	}
	print(count);
	return 0;
}