package y202;

import java.io.IOException;
import java.util.ArrayList;

public class Main {
	static int nextInt() {
		int c;
		try {
			c = System.in.read();
			while(c != '-' && (c < '0' || c > '9')) c = System.in.read();
			if(c == '-') return -nextInt();
			int res = 0;
			while(c >= '0' && c <= '9') {
				res = res * 10 + c - '0';
				c = System.in.read();
			}
			return res;
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return -1;
	}
	public static void main(String[] args) {
		int LEN = 1002;
		int N = nextInt();
		ArrayList<int[]> B[][] = new ArrayList[LEN][LEN];
		int ans = 0;
		L:for(int i = 0; i < N; i++) {
			int x = nextInt();
			int y = nextInt();
			int ix = x/20;
			int iy = y/20;
			for(int dx = -1; dx <= 1; dx++)
				for(int dy = -1; dy <= 1; dy++) {
					int tx = ix + dx;
					int ty = iy + dy;
					if(tx < 0 || LEN <= tx || ty < 0 || LEN <= ty || B[tx][ty] == null)
						continue;
					for(int c[]: B[tx][ty]) {
						int ox = c[0];
						int oy = c[1];
						if((ox - x)*(ox - x) + (oy - y)*(oy - y) < 400) {
							continue L;
						}
					}
				}
			
			if(B[ix][iy] == null) {
				B[ix][iy] = new ArrayList<int[]>();
			}
			B[ix][iy].add(new int[]{x, y});
			ans++;
		}
		System.out.println(ans);
	}
}