using System;
using System.Collections.Generic;
using System.Text;
using System.Linq;
 
class Program
{
    public void Proc()
    {
        Reader.IsDebug = false;
        int coinCount = int.Parse(Reader.ReadLine());
        List<Ichien> coinList = new List<Ichien>();
        for(int i=0; i<coinCount; i++) {
            Ichien newCoin = new Ichien(Reader.GetInt());
            bool isKasanari = false;
            coinList.Where(a=> a.X < newCoin.X + 20 && a.X > newCoin.X - 20 && a.Y < newCoin.Y + 20 && a.Y > newCoin.Y - 20).ToList().ForEach((b)=>{
                if(newCoin.IsKasanaru(b)) {
                    isKasanari = true;
                }
            });
            if(!isKasanari) {
                coinList.Add(newCoin);
            }
        }
        Console.WriteLine(coinList.Count);


    }
    
    public class Ichien {
        public long X;
        public long Y;
        public int R = 10;
        
        public Ichien(int[] pos) {
            this.X = pos[0];
            this.Y = pos[1];
        }
        public bool IsKasanaru(Ichien target) {
            long range = ((this.X - target.X) * (this.X - target.X)) + ((this.Y - target.Y) * (this.Y - target.Y));
            return (this.R + target.R) * (this.R + target.R) > range;
        }
    }


    public class Reader
    {
        public static bool IsDebug = true;
        private static String PlainInput = @"


2
100 100
112 116


 
";
        private static System.IO.StringReader Sr = null;
        public static string ReadLine()
        {
            if (IsDebug)
            {
                if (Sr == null)
                {
                    Sr = new System.IO.StringReader(PlainInput.Trim());
                }
                return Sr.ReadLine();
            }
            else
            {
                return Console.ReadLine();
            }
        }
        public static int[] GetInt(char delimiter = ' ', bool trim = false)
        {
            string inptStr = ReadLine();
            if (trim)
            {
                inptStr = inptStr.Trim();
            }
            string[] inpt = inptStr.Split(delimiter);
            int[] ret = new int[inpt.Length];
            for (int i = 0; i < inpt.Length; i++)
            {
                ret[i] = int.Parse(inpt[i]);
            }
            return ret;
        }
    }
    static void Main()
    {
        Program prg = new Program();
        prg.Proc();
    }
}