package main

import (
	"bufio"
	"os"
	"strconv"
	"math"
	"fmt"
)

func main() {
	sc := NewScanner()
	N := sc.NextInt()
	X := make([]int, N)
	Y := make([]int, N)
	union := UnionInit(N)

	if N == 0 {
		fmt.Println(1)
		return
	}
	for i := 0; i < N; i++ {
		X[i] = sc.NextInt()
		Y[i] = sc.NextInt()
	}
	for i := 0; i < N; i++ {
		for j := i + 1; j < N; j++ {

			if math.Hypot(float64(X[i] - X[j]), float64(Y[i] - Y[j])) <= 10 {
				union.Union(i, j)
			}
		}
	}

	mx := 0.0
	for i := 0; i < N; i++ {
		for j := 0; j < N; j++ {
			if union.Same(i, j) {
				v := math.Hypot(float64(X[i] - X[j]), float64(Y[i] - Y[j]))

				if mx < v {
					mx = v
				}
			}
		}
	}
	fmt.Println(mx + 2)
}

type UnionTree struct {
	par  []int
	rank []int
}

func UnionInit(n int) UnionTree {
	c := UnionTree{}
	c.par = make([]int, n + 1)
	c.rank = make([]int, n + 1)

	for i := 1; i < n + 1; i++ {
		c.par[i] = i
	}
	return c
}

func (c UnionTree) Find(u int) int {
	if c.par[u] == u {
		return u
	}
	c.par[u] = c.Find(c.par[u])
	return c.par[u]
}

func (c UnionTree) Union(u, v int) {
	xRoot := c.Find(u)
	yRoot := c.Find(v)

	if c.rank[xRoot] > c.rank[yRoot] {
		c.par[yRoot] = xRoot
	} else if c.rank[xRoot] < c.rank[yRoot] {
		c.par[xRoot] = yRoot
	} else if xRoot != yRoot {
		c.par[yRoot] = xRoot
		c.rank[xRoot] = c.rank[yRoot] + 1
	}
}

func (c UnionTree) Same(u, v int) bool {
	return c.Find(u) == c.Find(v)
}
func (c UnionTree) Rank(u int) int {
	return c.rank[u]
}

type Scanner struct {
	r   *bufio.Reader
	buf []byte
	p   int
}

func NewScanner() *Scanner {
	rdr := bufio.NewReaderSize(os.Stdin, 1000)
	return &Scanner{r:rdr}
}
func (s *Scanner) Next() string {
	s.pre()
	start := s.p
	for ; s.p < len(s.buf); s.p++ {
		if s.buf[s.p] == ' ' {
			break
		}
	}
	result := string(s.buf[start:s.p])
	s.p++
	return result
}
func (s *Scanner) NextLine() string {
	s.pre()
	start := s.p
	s.p = len(s.buf)
	return string(s.buf[start:])
}
func (s *Scanner) NextInt() int {
	v, _ := strconv.Atoi(s.Next())
	return v
}
func (s *Scanner) NextInt64() int64 {
	v, _ := strconv.ParseInt(s.Next(), 10, 64)
	return v
}

func (s *Scanner) NextIntArray() []int {
	s.pre()
	start := s.p
	result := []int{}
	for ; s.p < len(s.buf) + 1; s.p++ {
		if s.p == len(s.buf) || s.buf[s.p] == ' ' {
			v, _ := strconv.ParseInt(string(s.buf[start:s.p]), 10, 0)
			result = append(result, int(v))
			start = s.p + 1
		}
	}

	return result
}
func (s *Scanner) NextInt64Array() []int64 {
	s.pre()
	start := s.p
	result := []int64{}
	for ; s.p < len(s.buf) + 1; s.p++ {
		if s.p == len(s.buf) || s.buf[s.p] == ' ' {
			v, _ := strconv.ParseInt(string(s.buf[start:s.p]), 10, 64)
			result = append(result, v)
			start = s.p + 1
		}
	}
	return result
}

func (s *Scanner) NextMap() map[int]bool {
	s.pre()
	start := s.p
	mp := map[int]bool{}
	for ; s.p < len(s.buf); s.p++ {
		if s.buf[s.p] == ' ' {
			v, _ := strconv.Atoi(string(s.buf[start:s.p]))
			mp[v] = true
			start = s.p + 1
		}
	}
	v, _ := strconv.Atoi(string(s.buf[start:s.p]))
	mp[v] = true

	return mp
}

func (s *Scanner) pre() {
	if s.p >= len(s.buf) {
		s.readLine()
		s.p = 0
	}
}
func (s *Scanner) readLine() {
	s.buf = make([]byte, 0)
	for {
		l, p, e := s.r.ReadLine()
		if e != nil {
			panic(e)
		}
		s.buf = append(s.buf, l...)
		if !p {
			break
		}
	}
}