import java.util.*;

public class Main {
	public static void main (String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int w = 101;
		int h = 101;
		ArrayList<ArrayList<Point>> field = new ArrayList<>();
		for (int i = 0; i < w * h; i++) {
		    field.add(new ArrayList<>());
		}
		int count = 0;
		for (int i = 0; i < n; i++) {
		    Point p = new Point(sc.nextInt(), sc.nextInt());
		    int x = p.x / 200;
		    int y = p.y / 200;
		    boolean canSet = true;
		    for (int j = Math.max(0, x - 1); j <= Math.min(100, x + 1) && canSet; j++) {
		        for (int k = Math.max(0, y - 1); k <= Math.min(100, y + 1) && canSet; k++) {
		            for (Point z : field.get(j * w + k)) {
		                canSet = z.diff(p);
		                if (!canSet) {
		                    break;
		                }
		            }
		        }
		    }
		    if (canSet) {
		        field.get(x * w + y).add(p);
		        count++;
		    }
		}
		System.out.println(count);
	}
	
	static class Point {
	    int x;
	    int y;
	    
	    public Point(int x, int y) {
	        this.x = x;
	        this.y = y;
	    }
	    
	    public boolean diff(Point p) {
	        return (x - p.x) * (x - p.x) + (y - p.y) * (y - p.y) >= 20 * 20;
	    }
	}
}