#include<iostream>
#include<algorithm>
#include<string>
#include<vector>

using namespace std;

void solve202(){
	int N;
	cin >> N;
	int x, y;
	int ans = 0;
	vector<vector<int> > map(20000, vector<int>(20000));
/*	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++)
	{


		cin >> x >> y;
		
		if (map[x][y] == -1)
			continue;
		for (int i = -20; i <= 20; i++)
		{
			for (int j = -20; j <= 20; j++)
			{
				if ((abs(x + i)*abs(x + i) + abs(y + j)*abs(y + j)) <= 400){
					if (x+i >= 0 && y+j >= 0)
						map[x + i][y + j] = -1;
				}
			}
		}
		ans++;

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