#include<iostream>
#include<algorithm>
#include<string>
#include<vector>
#include<set>
using namespace std;


void solve202(){
	int N;
	cin >> N;
	vector<int> Input_X(N);
	vector<int> Input_Y(N);
	int MAX_X,MAX_Y;
	MAX_X = MAX_Y = 0;
	for (int i = 0; i < N; i++)
	{
		cin >> Input_X[i] >> Input_Y[i];
		MAX_X = max(MAX_X, Input_X[i]);
		MAX_Y = max(MAX_Y, Input_Y[i]);
	}
	

	set<pair<int, int> > map;

	int ans = 0;
/*	for (int i = 0; i < 20000; i++)
	{
		for (int j = 0; j < 20000; j++)
		{
			map[i][j] = 0;
		}
	}*/
	for (int count = 0; count < N; count++)
	{


		int x, y;
		x = Input_X[count];
		y = Input_Y[count];
		
		bool flag = true;
		for (int i = -20; i <= 20; i++)
		{
			for (int j = -20; j <= 20; j++)
			{
				if ((abs( i)*abs( i) + abs( j)*abs( j)) < 400){
					if(map.find(make_pair(x+i,y+j)) != map.end())
						flag = false;
				}
			}
		}
		//cout << x << " " << y << " "<<map[x][y]<< endl;
		if (flag)
		{
			ans++;
			map.insert(make_pair(x, y));
		}

	}
	cout << ans << endl;
}
int main(){
	solve202();
	return 0;
}