using System;
using System.IO;
using System.Linq;
using System.Text;
using System.Collections.Generic;
using System.Diagnostics;
using System.Numerics;
using Enu = System.Linq.Enumerable;

class Program
{
    Dictionary<Point, List<Point>> Dic = new Dictionary<Point, List<Point>>();

    public void Solve()
    {
        int N = Reader.Int();
        for (int i = 0; i < N; i++)
        {
            int x = Reader.Int(), y = Reader.Int();
            if (OK(x, y)) Add(x, y);
        }
        Console.WriteLine(Dic.Values.Sum(list => list.Count));
    }

    private bool OK(int x, int y)
    {
        int tx = x / 10, ty = y / 10;
        for (int nx = tx - 2; nx <= tx + 2; nx++)
            for (int ny = ty - 2; ny <= ty + 2; ny++)
            {
                var key = new Point(nx, ny);
                if (Dic.ContainsKey(key))
                    foreach (var p in Dic[new Point(nx, ny)])
                        if ((p.X - x) * (p.X - x) + (p.Y - y) * (p.Y - y) < 400) return false;
            }
        return true;
    }

    private void Add(int x, int y)
    {
        var key = new Point(x / 10, y / 10);
        if (!Dic.ContainsKey(key)) Dic[key] = new List<Point>();
        Dic[key].Add(new Point(x, y));
    }

    struct Point : IEquatable<Point>
    {
        public int X, Y;
        public Point(int x, int y) { X = x; Y = y; }
        public bool Equals(Point B) { return X == B.X && Y == B.Y; }
        public override int GetHashCode() { return X * 10000 + Y; }
    }
}


class Entry { static void Main() { new Program().Solve(); } }
class Reader
{
    private static TextReader reader = Console.In;
    private static readonly char[] separator = { ' ' };
    private static readonly StringSplitOptions op = StringSplitOptions.RemoveEmptyEntries;
    private static string[] A = new string[0];
    private static int i;
    private static void Init() { A = new string[0]; }
    public static void Set(TextReader r) { reader = r; Init(); }
    public static void Set(string file) { reader = new StreamReader(file); Init(); }
    public static bool HasNext() { return CheckNext(); }
    public static string String() { return Next(); }
    public static int Int() { return int.Parse(Next()); }
    public static long Long() { return long.Parse(Next()); }
    public static double Double() { return double.Parse(Next()); }
    public static int[] IntLine() { return Array.ConvertAll(Split(Line()), int.Parse); }
    public static int[] IntArray(int N) { return Enu.Range(0, N).Select(i => Int()).ToArray(); }
    public static int[][] IntTable(int H) { return Enu.Range(0, H).Select(i => IntLine()).ToArray(); }
    public static string[] StringArray(int N) { return Enu.Range(0, N).Select(i => Line()).ToArray(); }
    public static string Line() { return reader.ReadLine().Trim(); }
    private static string[] Split(string s) { return s.Split(separator, op); }
    private static string Next() { CheckNext(); return A[i++]; }
    private static bool CheckNext()
    {
        if (i < A.Length) return true;
        string line = reader.ReadLine();
        if (line == null) return false;
        if (line == "") return CheckNext();
        A = Split(line);
        i = 0;
        return true;
    }
}