using System;
using System.Collections.Generic;
using System.Linq;

namespace Yukicoder
{
    public class UF
    {
        private int[] _parent;
        private int[] _rank;

        public UF(int count)
        {
            _parent = new int[count];
            _rank = new int[count];
            for (int i = 0; i < _parent.Length; i++)
            {
                _parent[i] = i;
            }
        }

        private int Find(int value)
        {
            var parent = _parent[value];
            if (parent == value)
            {
                return value;
            }
            _parent[value] = Find(parent);
            return _parent[value];
        }

        public void Combine(int left, int right)
        {
            var leftParent = Find(left);
            var rightParent = Find(right);
            if (leftParent == rightParent)
            {
                return;
            }
            var leftRank = _rank[leftParent];
            var rightRank = _rank[rightParent];
            if (leftRank < rightRank)
            {
                _parent[leftParent] = rightParent;
                _rank[rightParent]++;
                return;
            }
            _parent[rightParent] = leftParent;
            _rank[leftParent]++;
        }

        public bool IsSameRoot(int left, int right)
        {
            return Find(left) == Find(right);
        }
    }

    class Program
    {
        static double GetDistance(int x1, int y1, int x2, int y2)
        {
            var dx = x1 - x2;
            var dy = y1 - y2;
            return Math.Abs(Math.Sqrt(dx*dx + dy*dy));
        }

        static void Main(string[] args)
        {
            var n = int.Parse(Console.ReadLine());            
            int[] xPosition = new int[n];
            int[] yPosition = new int[n];
            for (int i = 0; i < n; i++)
            {
                var line = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
                xPosition[i] = line[0];
                yPosition[i] = line[1];
            }
            if (n == 0)
            {
                Console.WriteLine(1);
                return;
            }

            var unionFind = new UF(n);
            for (int i = 0; i < n; i++)
            {
                for (int j = 0; j < i; j++)
                {
                    var distance = GetDistance(xPosition[i], yPosition[i], xPosition[j], yPosition[j]);
                    if(distance < 10 + 1e-10)
                    {
                        unionFind.Combine(i, j);
                    }
                }
            }
            var maxDistance = 0d;
            for (int i = 0; i < n; i++)
            {
                for (int j = 0; j < i; j++)
                {
                    if (unionFind.IsSameRoot(i, j))
                    {
                        var distance = GetDistance(xPosition[i], yPosition[i], xPosition[j], yPosition[j]);
                        maxDistance = Math.Max(maxDistance, distance);
                    }
                }
            }
            Console.WriteLine(maxDistance + 2);
        }
    }
}