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

class Program
{
    static void Main(string[] args)
    {
        new Magatro().Solve();
    }
}

public class Magatro
{
    private int N;
    P[] XY;
    int[] Par;
    List<int>[] List;

    private void Scan()
    {
        N = int.Parse(Console.ReadLine());
        XY = new P[N];
        for (int i = 0; i < N; i++)
        {
            string[] s = Console.ReadLine().Split(' ');
            XY[i] = new P(int.Parse(s[0]), int.Parse(s[1]));
        }
    }

    private void Union(int a, int b)
    {
        a = Root(a);
        b = Root(b);
        if (a == b) return;
        Par[b] = a;
        foreach (int i in List[b])
        {
            List[a].Add(i);
        }
    }

    private int Root(int a)
    {
        return Par[a] == a ? a : Root(Par[a]);
    }

    private bool Same(int a, int b)
    {
        return Root(a) == Root(b);
    }

    public void Solve()
    {
        Scan();
        if( N == 0)
        {
            Console.WriteLine(1);
            return;
        }
        Par = new int[N];
        List = new List<int>[N];
        for (int i = 0; i < N; i++)
        {
            Par[i] = i;
            List[i] = new List<int>();
            List[i].Add(i);
        }

        for (int i = 0; i < N - 1; i++)
        {
            for (int j = i + 1; j < N; j++)
            {
                if (Dist(XY[i], XY[j]) <= 10 * 10)
                {
                    Union(i, j);
                }
            }
        }

        var hs = new HashSet<int>();
        int ans = 0;
        for (int i = 0; i < N; i++)
        {
            int j = Root(i);
            if (!hs.Add(j)) continue ;
            for (int k = 0; k < List[j].Count - 1; k++)
            {
                for (int l = k + 1; l < List[j].Count; l++)
                {
                    ans = Math.Max(Dist(XY[List[j][k]], XY[List[j][l]]), ans);
                }
            }
        }

        Console.WriteLine(Math.Sqrt(ans) + 2);
    }

    public int Dist(P a, P b)
    {
        return (a.X - b.X) * (a.X - b.X) + (a.Y - b.Y) * (a.Y - b.Y);
    }
}

public struct P
{
    public int X, Y;
    public P(int x, int y)
    {
        X = x;
        Y = y;
    }
}