import java.io.File;
import java.util.*;

public class Main {
	public static void main(String[] args){
		// TODO 自動生成されたメソッド・スタブ
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		HashSet<Integer> xSet = new HashSet<>();
		HashSet<Integer> ySet = new HashSet<>();
		int ans=0;
		int x,y;
		for(int k=0;k<n;k++){
			boolean check = true;
			 x = sc.nextInt();
			 y = sc.nextInt();
			for(int i=Math.max(0, x-19);(i<=Math.min(2000, x+19)&&check);i++){
				int dy = (int) Math.sqrt(399-(i-x)*(i-x)+0.001);
				for(int j=Math.max(0, y-dy);j<=Math.min(2000, y+dy);j++){
					if(xSet.contains(i)&&ySet.contains(j)) check=false;
				}
				
			}
			if(check){
				ans++;
				xSet.add(x);
				ySet.add(y);
				}
		}
		System.out.println(ans);
	}
}