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

class Program
{
    void Solve()
    {
        int N = reader.Int();
        var Pos = reader.IntGrid(N);
        double ans = 1;
        var uf = new UnionFind(N);
        Func<int, int> Pow = n => n * n;
        Func<int, int, int> D2 = (a,b) => Pow(Pos[a][0]-Pos[b][0]) + Pow(Pos[a][1]-Pos[b][1]);

        for (int a = 0; a < N; a++)
            for (int b = a + 1; b < N; b++)
                if (D2(a,b) <= 100)
                    uf.Unite(a, b);
        for (int a = 0; a < N; a++)
            for (int b = a; b < N; b++)
                if (uf.Same(a, b))
                    ans = Math.Max(ans, Math.Sqrt(D2(a, b)) + 2);

        Console.WriteLine(ans);
    }

    class UnionFind
    {
        private int[] parent;
        private int[] rank;
        private int[] numElements;

        public UnionFind(int N)
        {
            parent = new int[N];
            rank = new int[N];
            numElements = new int[N];
            for (int i = 0; i < N; i++)
            {
                parent[i] = i;
                numElements[i] = 1;
            }
        }
        public int Root(int x)
        {
            if (parent[x] == x) return x;
            return parent[x] = Root(parent[x]);
        }
        public bool Same(int x, int y)
        {
            return Root(x) == Root(y);
        }
        public int NumElements(int x)
        {
            return numElements[Root(x)];
        }
        public void Unite(int x, int y)
        {
            x = Root(x); y = Root(y);
            if (x == y) return;
            if (rank[x] < rank[y])
            {
                parent[x] = y;
                numElements[y] += numElements[x];
            }
            else
            {
                parent[y] = x;
                if (rank[x] == rank[y]) { rank[x]++; }
                numElements[x] += numElements[y];
            }
        }
    }



    Reader reader = new Reader(Console.In);
    static void Main() { new Program().Solve(); }
}

class Reader
{
    private readonly TextReader reader;
    private readonly char[] separator = { ' ' };
    private readonly StringSplitOptions removeOp = StringSplitOptions.RemoveEmptyEntries;
    private string[] A = new string[0];
    private int i;

    public Reader(TextReader r) { reader = r; }
    public Reader(string file) { reader = new StreamReader(file); }
    public bool HasNext() { return Enqueue(); }
    public string String() { return Dequeue(); }
    public int Int() { return int.Parse(Dequeue()); }
    public long Long() { return long.Parse(Dequeue()); }
    public double Double() { return double.Parse(Dequeue()); }
    public int[] IntLine() { var s = Line(); return s == "" ? new int[0] : Array.ConvertAll(Split(s), int.Parse); }
    public int[] IntArray(int N) { return Enu.Range(0, N).Select(i => Int()).ToArray(); }
    public int[][] IntGrid(int H) { return Enu.Range(0, H).Select(i => IntLine()).ToArray(); }
    public string[] StringArray(int N) { return Enu.Range(0, N).Select(i => Line()).ToArray(); }
    public string Line() { return reader.ReadLine().Trim(); }
    private string[] Split(string s) { return s.Split(separator, removeOp); }
    private bool Enqueue()
    {
        if (i < A.Length) return true;
        string line = reader.ReadLine();
        if (line == null) return false;
        if (line == "") return Enqueue();
        A = Split(line);
        i = 0;
        return true;
    }
    private string Dequeue() { Enqueue(); return A[i++]; }
}